Can we agree, to work as a translator and/or as an interpreter one should achieve level S-4 (Full professional proficiency)
How often you use your 2nd/3rd languages, how often you read, write, listen and/or speak in those languages.
you know the old saying "If you don't use it, you loose it" plus languages are a living things, they grow, change, adapt, and borrow. Certain terms overtime could loose their meanings and end up meaning completely a different thing, so the question is how immersed are you in your languages.