Pre-select language of term search with GUI-language

If the current GUI language exists as available language of the term search in the termPortal, select this language as pre-selected search language on opening the termPortal.

If the GUI-language is "de" and only de-AT or de-DE is available in the termSearch, pre-select the first matching sub-language, that starts with "de" (of course analogous for other languages).

if the GUI-language is "de-DE" and only "de" is available as search-language in the termPortal, pre-select "de" in the termPortal. (analogous for other languages).

Server side implementation makes sense in this regard, I guess.