robinm I see, is there any reason for this?
In the case of PureData we are running libpd inside a C++ program that contains all the Bela I/O ("we added Pd support to a Bela project"). In the case of SuperCollider we added a Bela backend to scsynth
("we added Bela support to scsynth"). While there are ways of embedding libscsynth (Sc's equivalent to libpd) into any arbitrary C++ program, we haven't done that. So sure it can be done but it takes plenty of effort and almost always (like in this case) you'll find that the other solutions are much easier.
robinm A little more to study before I can properly handle this but thanks for the hints
Well if you are happy with what the program does (i.e.: work as a stand-alone Trill-OSC transceiver), then you don't need to write any C++ at all, just have it run alongside your Sc program. I don't have an example for that at the moment because I am really bad at Supercollider, but the enclosed PureData one should make it obvious.
I appreciate jreus's effort to get the Trill ugens up and running, but I'd rather people use this approach instead as it is arguably easier to maintain. Anyhow, let me have a look at that issue.