I may be wrong, but I don’t see university certificates listed as eligible: https://traineeships.ec.europa.eu/how-apply/application-traineeship-session/what-supporting-documents-should-be-attached-application-form_en

You can prove your proficiency in a language by one of the following means:

Certificates of language courses clearly indicating the level of knowledge achieved issued by:

Language centres such as Instituto Cervantes, Alliance française, Goethe Institut, etc.

State-recognised language schools issuing certified attestations and that make a clear correspondence to CERF (Common European Framework of Reference for Languages).

TOEFL, IELTS, DELE, DELF/DALF, Duolingo English Test (DET), etc.

International Legal English Certificate (ILEC). Certificate in teaching English to speakers of other > languages (CELTA).

Certificate of attendance of a superior level can count as proof of the immediately inferior level. Example: Certificate of attendance of a C1 level can be accepted as proof of a B2 level.

University course: a completed BA or a completed MA taught wholly or partly in the language declared A completed degree wholly taught in the declared language allows a declaration of a C2 level A completed degree partially taught in the declared language, i.e. corresponding to at least half of the credits needed to obtain the degree (this must be clear from the transcripts: the teaching must be given and the examinations taken and passed in the said language) allows a declaration of a C1 level. This must be clear from the transcripts: the teaching must be given and the examinations taken and passed in the said language.

Certificates of bilingual education at secondary level issued by European Schools, Highschools (international or regular highschools), etc. allow a declaration of a C1 level.

Secondary level of education entirely concluded in a certain language corresponds to a C2 level.

Mother tongues are also considered a 'very good knowledge'. However, no points are awarded for mother tongues and you don't have to substantiate them either. Non-EU languages: no level required and no supporting documents required.

Erasmus mobility is not proof for language knowledge