How to fix interference between NewDocumentEnvironment and enumitem package

Question

I'm trying to write a couple of new environments and commands to save short answers from a list with enumerate environment, the idea being to save the first and second level using references to lists stored in memory.

I am using the enumitem, multicol, pgffor, tcolorbox and xparse packages.

I explained, I created two new environments each with a defined command inside them to be able to save the short answers and I added a pair of keys to enumitem.

\NewDocumentEnvironment{saveanswer} whit \answi
\NewDocumentEnvironment{saveansweri} whit \answii
\SetEnumitemKey{columns}{before=\begin{multicols}{#1},after=\end{multicols}}%
\SetEnumitemKey{savekey}{before=\begin{saveanswer}{#1},after=\end{saveanswer}}%
\SetEnumitemKey{ansref}{before=\begin{saveansweri}{#1},after=\end{saveansweri}}%

Here begins my dilemma. If I use the enumitem keys, it loses the alignment of the lists in the last element and affects all enumerate environments (with or without the enabled key)

If I comment the enumitem keys and encapsulate the enumerate environments within "saveanswer" the ones I have created partially solve the issue, but it still affects the other enumerate environments.

With both cases it fails, in addition, I can not run the foreach loop to keep the items correctly in the list. I would like it to look like this:

I'm a little lost in this, i read Conflict between NewDocumentEnvironment and enumerate and maybe the way to get what I'm looking for is not the right one and it should be done differently. Regards: The MWE:

% !file: forum.tex
% arara: pdflatex
% arara: clean: { files:[forum.aux, forum.log] }
\documentclass{article}
\usepackage{enumitem}
\usepackage{multicol}
\usepackage{pgffor}
\usepackage{tcolorbox}
\tcbuselibrary{many}
\pagestyle{empty}

% Set key for multicols in enumitem
\SetEnumitemKey{columns}{before=\begin{multicols}{#1},after=\end{multicols}}%
\SetEnumitemKey{savekey}{before=\begin{saveanswer}{#1},after=\end{saveanswer}}%
\SetEnumitemKey{ansref}{before=\begin{saveansweri}{#1},after=\end{saveansweri}}%

% Some definition
\newtheorem{theorem}{Theorem}
\newtheorem{exercise}[theorem]{Exercise}

% Adapted from https://tex.stackexchange.com/a/364763/7832
\ExplSyntaxOn
% Reporter macro, is expandable
\cs_new:Npn \reportnumberofseqitems #1{%
 \seq_count:c {l_bcp_data_#1_seq}%
}
\NewDocumentCommand{\storedata}{mm}
  {
   \bcp_store_data:nn { #1 } { #2 }
  }

\NewDocumentCommand{\appenddata}{+m+m}
 {
  \bcp_append_data:nn { #1 } { #2 }
 }

\DeclareExpandableDocumentCommand{\getdata}{O{1}m}
 {
  \bcp_get_data:nn { #1 } { #2 }
 }

\cs_new_protected:Npn \bcp_store_data:nn #1 #2
 {
  % create the sequence if it doesn't exist or clear it if it exists
  \seq_if_exist:cTF { l_bcp_data_#1_seq }
   { \seq_new:c { l_bcp_data_#1_seq } }
   { \seq_gclear:c { l_bcp_data_#1_seq } }
  % append the items
  \__bcp_append_data:nn { #1 } { #2 }
 }

\cs_new_protected:Npn \bcp_append_data:nn #1 #2
 {
  % create the sequence if it doesn't exist, do nothing if it exists
  \seq_if_exist:cF { l_bcp_data_#1_seq }
   { \seq_new:c { l_bcp_data_#1_seq } }
  % append the items
  \__bcp_append_data:nn { #1 } { #2 }
 }

\cs_new_protected:Npn \__bcp_append_data:nn #1 #2
 {
  % append items one at a time
  \tl_map_inline:nn { #2 }
   {
    \seq_gput_right:cn { l_bcp_data_#1_seq } { ##1 }
   }
 }

\cs_new:Npn \bcp_get_data:nn #1 #2
 {
  % retrieve the requested item
  \seq_item:cn { l_bcp_data_#2_seq } { #1 }
 }
% Save answer in first level answi 
\NewDocumentEnvironment{saveanswer}{m}{%
\NewDocumentCommand\answi{m}{%,
    \appenddata{#1}{{##1}}%
    }% close \answi
}{%
}% close saveanswer

% Save answer in second level answii 
\newcounter{myNo}
\NewDocumentEnvironment{saveansweri}{m}{%
\stepcounter{myNo}
\NewDocumentCommand\answii{m}{%,
    \appenddata{#1:\themyNo}{{##1}}%
    }% close \answii
}{%
\appenddata{#1}{{\begin{enumerate}\space%
\foreach \x in {1,...,\reportnumberofseqitems{#1:\themyNo}}{%
    \item \space \getdata[\x]{#1:\themyNo} \space%
                } % close foreach
    \space \end{enumerate}}} % close appendata
}% close saveansweri

\ExplSyntaxOff

% [#1] : pass to tcolorbox
% {#2} : title
% {#3} : list ref
% [#4] : columns
\DeclareTotalTColorBox{\showans}{O{} m m O{4}}
{ colback=white,size=small,top=0mm,bottom=1.5mm, left=0mm,width=\columnwidth,title filled,%
  fontupper=\small,fonttitle=\small\sffamily,%
    adjusted title={#2},center title,#1}
  {% 
  \begin{enumerate}[columns=#4,leftmargin=15pt,labelsep=3pt,font=\footnotesize,nosep,widest=25,]%
  \small
  \setlength{\columnsep}{0pt} 
   \foreach \x in {1,...,\reportnumberofseqitems{#3}} {
    \item \getdata[\x]{#3}%
    }
  \end{enumerate}
  }%
\begin{document}

\section{It looks like this}
\subsection{Exercices}
\begin{enumerate}[savekey=test1]
\setenumerate{labelsep=5pt, leftmargin=1cm, itemsep=0pt,widest=80}%
\item True False
      \begin{enumerate}[ansref=test1] 
      \item $2\alpha+2\delta=90^{\circ}$ \answii{True}
      \item $\angle EDF=45^{\circ}$ \answii{False}
      \end{enumerate} 
\item Factor $x^{2}-2x+1$  \answi{$\left(x-1\right)^{2}$} 
\item Factor$3x+3y+3z$    \answi{$3(x+y+z)$}
\item True False
      \begin{enumerate}[ansref=test1]
      \item $2\alpha+2\delta=90^{\circ}$ \answii{False}
      \item $\alpha=\delta$ \answii{True}
      \item $\alpha=\delta$ \answii{True}
      \end{enumerate} 
\end{enumerate}
\subsection{answers}
\showans{Exercices 1}{test1}[2]
\end{document}

Answer 1

I am applying a different strategy, by automatic stepping down and up of enumerate levels and storing the \begin{enumerate} and \end{enumerate} into one single list, retrieving the current list id with global \prop variable.

% !file: forum.tex
% arara: pdflatex
% arara: clean: { files:[forum.aux, forum.log] }
\documentclass{article}
\usepackage{enumitem}
\usepackage{multicol}
\usepackage{pgffor}
\usepackage[many]{tcolorbox}
\pagestyle{empty}

% Set key for multicols in enumitem
\SetEnumitemKey{columns}{before=\begin{multicols}{#1},after=\end{multicols}}%
\SetEnumitemKey{savekey}{before={\storecurrentid{#1}\begin{saveanswer}{#1}},after=\end{saveanswer}}%

% Some definition
\newtheorem{theorem}{Theorem}
\newtheorem{exercise}[theorem]{Exercise}

% Adapted from https://tex.stackexchange.com/a/364763/7832
\ExplSyntaxOn

\prop_new:N \g_bpc_admin_prop 

\cs_new:Npn \storecurrentid #1{%
  \prop_gput:Nnn \g_bpc_admin_prop {current-id} {#1}
}

\cs_new:Npn \retrievecurrentid {%
  \prop_item:Nn \g_bpc_admin_prop {current-id} 
}


\NewDocumentEnvironment{saveanswer}{m}{%
  \setlist[enumerate,1]{labelsep=5pt, leftmargin=1cm, itemsep=0pt,widest=80}%
  \setlist[enumerate,2]{before={\stepdownlevel},after={\stepuplevel},labelsep=5pt, leftmargin=0.6cm, itemsep=0pt,widest=80}
  \seq_if_exist:cF { l_bcp_data_#1_seq }{%
    \seq_new:c { l_bcp_data_#1_seq }
  }
  \leavevmode
}{%
%
}% close saveanswer

\NewDocumentCommand{\answeris}{+m}{%
  \seq_gput_right:cn { l_bcp_data_ \retrievecurrentid _seq }{\item  #1}
  \par
}

\newcommand{\stepdownlevel}{%
  % Must start a new item with \begin{enumerate} on answer ... 
  \seq_gput_right:cn {l_bcp_data_ \retrievecurrentid _seq} {\item \begin{enumerate}}
  }

\newcommand{\stepuplevel}{%
  % Close current enumerate level
  \seq_gput_right:cn {l_bcp_data_ \retrievecurrentid _seq} {\end{enumerate}}
}

\cs_new:Npn \displayseqcontent #1#2 {%
  \seq_if_empty:cF { l_bcp_data_#1_seq } {%
    \seq_log:c { l_bcp_data_#1_seq }
    \setlist[enumerate,2]{before={},after={},labelsep=5pt, leftmargin=0.6cm, itemsep=0pt,widest=80}
    \begin{enumerate}[#2]
      \small
      \setlength{\columnsep}{0pt} 
      \seq_map_inline:cn { l_bcp_data_#1_seq } {%
        ##1%
      }
    \end{enumerate}
  }
}

\ExplSyntaxOff

% [#1] : pass to tcolorbox
% {#2} : title
% {#3} : list ref
% [#4] : columns
\DeclareTotalTColorBox{\showans}{O{} m m O{4}}
{ colback=white,size=small,top=0mm,bottom=1.5mm, left=0mm,width=\columnwidth,title filled,%
  fontupper=\small,fonttitle=\small\sffamily,%
  adjusted title={#2},center title,#1}
{% 
  \displayseqcontent{#3}{columns=#4,leftmargin=15pt,labelsep=3pt,font=\footnotesize,nosep,widest=25}
}%


% Set the list properties for level 1 and 2
%\setlist[enumerate,1]{labelsep=5pt, leftmargin=1cm, itemsep=0pt,widest=80}%
%\setlist[enumerate,2]{before={\stepdownlevel},after={\typeout{stepping up for \retrievecurrentid}\stepuplevel},labelsep=5pt, leftmargin=0.6cm, itemsep=0pt,widest=80}%

\begin{document}
\section{It looks like this}
\subsection{Exercices}
\begin{enumerate}[savekey=test1]
\item True False
  \begin{enumerate}
  \item $2\alpha+2\delta=90^{\circ}$ \answeris{True}
  \item $\angle EDF=45^{\circ}$ \answeris{False}
  \end{enumerate} 
\item Factor $x^{2}-2x+1$  \answeris{$\left(x-1\right)^{2}$} 
\item Factor $3x+3y+3z$    \answeris{$3(x+y+z)$}
\item True False
  \begin{enumerate}
  \item $2\alpha+2\delta=90^{\circ}$ \answeris{False}
  \item $\alpha=\delta$ \answeris{True}
  \item $\alpha > \delta$ \answeris{False}
  \item \LaTeX2e\ is cool? \answeris{Very True!}
  \end{enumerate} 
\end{enumerate}


\begin{enumerate}[savekey=test2]
\item True False 
  \begin{enumerate}
  \item $2\alpha+2\delta=90^{\circ}$ \answeris{False}
  \item $\alpha=\delta$ \answeris{True}
  \item $\alpha > \delta$ \answeris{False}
  \item \LaTeX2e\ is cool? \answeris{Very True!}
  \end{enumerate} 

\item True False 

  \begin{enumerate}
  \item $2\alpha+2\delta=90^{\circ}$ \answeris{True}
  \item $\angle EDF=45^{\circ}$ \answeris{False}
  \end{enumerate} 

\item Factor $x^{2}-2x+1$  \answeris{$\left(x-1\right)^{2}$} 

\item Factor $3x+3y+3z$    \answeris{$3(x+y+z)$}
\end{enumerate}


\subsection{answers}

\showans[colback=yellow!30!white]{Exercices 1}{test1}[2]

\showans[colback=yellow!30!white]{Exercices 2}{test2}[2]


\showans[colback=yellow!70!blue]{Exercices 1 again}{test1}[2]
\end{document}