Thanks for the feedback, and I think your english seems great. 🙂
Regarding OSL, I think my colleague misunderstood what you were referring to. I would say, first, that this is not something to look for in the near term, as we have many other core features yet to implement (as you mention, motion blur, volumetrics, etc). And second, though we are open to the idea, it ultimately depends on a pretty careful evaluation, to see if/how it can be integrated with Bella’s internal architecture.
Regarding skin, we think it will probably be best to implement something like a custom skin material node (or a layer-like node), rather than try to handle it generically, since there exist a few nice cheats/hacks specifically created for rendering skin.
As for multiple bsdfs, it should already be possible using the blend & stack materials, so please feel free to let us know if/how those are unable to help you achieve whatever it is you are attempting to do.