PeerTube is not a single website, but a federation of several videoplatforms.
There are videos in many langages, he host a search engine here : https://sepiasearch.org/
We are currently working on improving the search and recommandations engine to better support langages.
Before translating videos, we need speech-to-text transcription. We are in contact with contributors who want to bring such a feature to PeerTube so... finger crossed !