KOMA chapter titles: same height for numbered and unnumbered chapters

Question

I've formated my chapter titles with KOMA options to make the chapter number appear above the chapter title. Unfortunately, I couldn't figure out how to let both chapter names start at the same heigth. This picture shows the output of my current MWE. Maybe someone can help me with this problem. Thanks in advance!

\documentclass[
a4paper,
10pt,
listof=totoc,
bibliography=totoc,
twoside,
]{scrreprt}

\usepackage[no-math]{fontspec}
\PassOptionsToPackage{no-math}{fontspec}
\usepackage[showframe]{geometry}
\usepackage{blindtext}
\usepackage{footnotebackref}

\hypersetup{pdfpagelayout=TwoPageRight}
\setlength{\parindent}{0pt}

\KOMAoptions{chapterprefix=true}
\renewcommand{\raggedchapter}{\raggedleft}
\renewcommand{\chapapp}{}
\RedeclareSectionCommand[
    prefixfont = \bfseries\fontsize{50}{52}\selectfont,
    font = \Huge,
    beforeskip = 40pt,
    innerskip = 0pt,
    afterskip = 40pt,
]{chapter}


\begin{document}

\chapter*{Unnumbered Chapter} \addcontentsline{toc}{chapter}{Unnumbered Chapter}
\blindtext
\chapter{Numbered Chapter}
\blindtext

\end{document}

Answer 1

You can redefine \chapterlineswithprefixformat:

\documentclass[
  %a4paper,% default
  10pt,
  listof=totoc,
  bibliography=totoc,
  twoside
]{scrreprt}

\usepackage[no-math]{fontspec}
\usepackage[showframe]{geometry}
\usepackage{blindtext}
\usepackage{footnotebackref}

\hypersetup{pdfpagelayout=TwoPageRight}
%\setlength{\parindent}{0pt}% use class option parskip=half or parskip=full

\KOMAoptions{chapterprefix=true}
\renewcommand*{\raggedchapter}{\raggedleft}
\renewcommand*{\chapterformat}{\thechapter}
\RedeclareSectionCommand[
    prefixfont = \bfseries\fontsize{50}{52}\selectfont,
    font = \Huge,
    beforeskip = 40pt,
    innerskip = 0pt,
    afterskip = 40pt,
]{chapter}

\makeatletter
\renewcommand*\chapterlineswithprefixformat[3]{%
  \Ifstr{#1}{chapter}
    {\IfArgIsEmpty{#2}
      {{\usekomafont{#1prefix}{%
          \mbox{}%
          \setlength{\@tempskipa}{\csname scr@#1@innerskip\endcsname}\chapterheadmidvskip
        }}#3%
      }% unnumbered chapter headings
      {#2#3}% numbered chapter headings
    }
    {#2#3}% other headings using style=chapter
}
\makeatother

\begin{document}
\addchap{Unnumbered Chapter}% unnumbered chapter with ToC entry
\blindtext
\chapter{Numbered Chapter}
\blindtext
\end{document}