Latest StaxRip test version has better support for MakeMKV output in case somebody interested:
http://www.stax76.bplaced.net/files/app ... 1.1.5.1.7z
One thing I noticed is MakeMKV use different three letter language code than mkvtoolnix, IIRC MakeMKV use deu for German and mkvtoolnix use ger, StaxRip will detect both so no problem.