The classical style guide currently says "Note: Only create translation works when you can source who the translator is on a recorded performance. Do not enter an "unknown English version" or similar; see "different versions" above."

https://wiki.musicbrainz.org/Style/Classical/Works#Translated_lyrics

This seems like strange advice. For example if you want to relate a recording to the english version of a song that already exists as a work in its original language, it makes total sense to create a new work in english, even if you don't know who translated it.

http://chatlogs.metabrainz.org/brainzbot/musicbrainz/2015-12-05/?msg=3423715&page=2