Error: Use of \@index doesn't match its definition

Question

First, let me show you something that works. It creates a link from an indexed term to its corresponding entry in the index, and vice-versa.

\newcommand{\myname}[2]{#1\renewcommand{\@currentlabel}{#2}}  % #1 is index entry; #2 is entry in the text

\begin{document}
\ref{314}\index{\myname{decision tree}{decision trees}\label{314}}
\end{document}

Now I want to automate this and write a macro called Index. I came up with this:

\newcommand{\myname}[2]{#1\renewcommand{\@currentlabel}{#2}}  % #1 is index entry; #2 is entry in the text
\newcommand{\Index}[2]{\index{\myname{#1}{#2}\label{#1}}}

\begin{document}
\Index{decision tree}{decision trees}
\end{document}

If I don't call the Index function in the main part, there is no error. But when I call it as in the above example, I get this error:

! Use of \@index doesn't match its definition.
\new@ifnextchar ...served@d = #1\def \reserved@a {
                                                  #2}\def \reserved@b {#3}\f...

I have very little experience with macros. I know that if I were to use my failing Index function everywhere, then run my Latex document through a Python script that expands the Index macro as it should, then compile the resulting expanded Latex source, it would work. So my macro does not expand the way I think it should. I am wondering what is wrong in my code.

Update: working example

Here is some stuff that works:

\documentclass[10pt]{article}
\usepackage{imakeidx}
\makeindex
\usepackage[nottoc]{tocbibind}
\usepackage[colorlinks = true, 
                   linkcolor = red]{hyperref}
\makeatletter
\newcommand{\myname}[2]{#1\renewcommand{\@currentlabel}{#2}}  
\newcommand{\Index}[2]{\index{\myname{#1}{#2}\label{#1}}}
\makeatother

\begin{document}
The technique presented here, called \ref{bvc}\index{\myname{decision tree!boosted tree}{boosted trees}\label{bvc}}, is used for ...
%The technique presented here, called \Index{decision tree!boosted tree}{boosted trees}, is used for ...
\printindex
\end{document}

Now if I replace the line inside the document body by the one commented out (my ultimate goal), that's when I get the compilation error. I suspect the implicitly nested \newcommand with a \renewcommand is the source of the problem.

Here is that output from the version that works (the one I posted above). On page 1:

Then on page 2 (the index page):

What I try to do is treat index entries as if they were equations, for referencing purposes. But the link to an equation is a counter. I want to avoid that and overwrite the counter by the target keyword. So it is equivalent to relabeling.

Answer 1

I'm not sure how pointing to the index is useful. Anyway…

\documentclass{article}
\usepackage{makeidx}
\usepackage{hyperref}

\makeindex

\newcounter{indexcount}
\NewDocumentCommand{\Index}{mm}{%
  % #1 is index entry; #2 is entry in the text
  \refstepcounter{indexcount}%
  \index{#1@#1\indexlabel{\theindexcount}}%
  \hyperref[index\theindexcount]{#2}%
}
\NewDocumentCommand{\indexlabel}{m}{\label{index#1}}

\begin{document}

Some text

\Index{decision tree}{decision trees}

\printindex

\end{document}