How to remove tag spam and set language in several MKV files at once

Instructions for OSX

(are practically identical to those for Linux, with the exception of the first line of the script.)

after you have installed the mkvtoolnix package, you open the editor of your choice and
copy this into it:

#!/usr/bin/env bash
for f in *.mkv
do
 echo -n $f  ' '  
 mkvpropedit --delete title --edit track:v1 --set language=jpn --set flag-forced=0 --delete name --edit track:a1 --set language=ger --set flag-forced=0 --delete name --edit track:a2 --set language=jpn --set flag-forced=0 --delete name --edit track:s1 --set language=ger --set flag-forced=1 --delete name --edit track:s2 --set language=ger --set flag-forced=0 --set name=full "${f}"
done

save it as setlangs.sh

then set the ‘execute’ flag on the script in terminal:
chmod +x setlangs.sh

The file is now ready for use.
Copy it into the folder with your MKV files, modify it according to the above guide, then execute it.