u/tamagotchiforever

I've never certified my English, but I've worked abroad and used the language so much that my fluency is almost native. As for German (which is not needed for the position I'm interested in) I hold a C1 diploma from a language school partnered with a German university, but I'm not sure if this is considered official enough.
I don't even know if language certificates are required, just wondering if anyone knows the answer?
I'm a bit nervous that they might be, because paying for Cambridge/Goethe/etc is very expensive.

It's my first time applying for a traineeship, and I'm considering using AI to draft my CV in case there's an ATS screening.
If there are any tips for CV building that new applicants should consider, please share your experience! Thanks a lot in advance.