\input regression-test.tex
\documentclass{article}
% Selectable languages are loaded into babel by their babel names, but no
% "map" is given.  With option "bcp47" (default true) langselect enables
% babel's tag-as-selector mapping, so \selectlanguage{de} resolves to ngerman.
\usepackage[ngerman,english]{babel}
\usepackage[
  languages={en,de},
  targetlang=de
]{langselect}
\begin{document}
\START
\TYPE{target=\olsTargetLanguage}
\TYPE{active=\languagename}
\lende{English}{Deutsch}
\END
\end{document}