Example: when using --prioritize-languages --sort-languages=en,ja --sort-regions=USA,EUR on the No-Intro Nintendo DS P/C dat, "Exit DS (USA) (En,Fr,De,Es,It)" gets chosen instead of "Exit DS (Europe) (En,Ja,Fr,De,Es,It)". I would expect it to choose the one with both specified languages.
Using the --debug flag I can find this in the log:
[main] i.g.datromtool.sorting.GameComparator : Under criteria 'Region selection', 'Exit DS (USA) (En,Fr,De,Es,It)' is preferred over 'Exit DS (Europe) (En,Ja,Fr,De,Es,It)'