I have no personal objection as a roleplayer with the use of foreign languages to substitute for actual foreign languages in the world we are inhabiting. As a roleplayer it lets me consciously keep myself in the dark about things I have no business knowing for my character.

As a reader I think it detracts from the joint story that we are writing and enjoying together as some of the nuance of the interactions require the use of a translator to attain.

Trying to balance between my enjoyment and the choices as a roleplayer and the choices I would make as a reader is sometimes hard.

I think they way I would encourage resolving this, is if only the characters who know the language or should know the language indulge in translation, (this requires the honor system). Or all language be handled in our accepted common dialect for writing, in this case english, and that writer discretion be used to limit meta gaming, (this also requires the honor system, but lets everyone enjoy the writing to the fullest in the process.)