I am then quite torn: keep using SuperCollider with all the accumulated UGens and example code, or switch to this elegant language and start over with a lot of basics... Leading to the question: any bridges or ways to integrate and reuse between the two?

I guess you know about them already, but TidalCycles / Strudel / Sardine / Bacalao / Overtone can be interesting to explore in this direction. Not specifically sapf-integration, but various ways of using SC with more elegant langs.

I wonder if AI could help you translate those or write a translater ? Idk if the language is complex tough