Thanks for reply, and thank you for considering MIDI learn.
Not sure that it really is what I am after, though.
What I was looking for was a way of recording the knob moves (live) on the (interapp) app itself, NOT learning some “component” in Cubasis to “mimic” the move only to move (and record) this as a rather sorry excuse for the real thing 
Why not just make it possible to activate “automation” (well, I guess its not exactly automation in this case, but you could activate “CC recording” for an interapp-track with the normal “W” - Write automation - on the track, or even better, just capture the CCs along with the notes during normal recording) and then record the movements of the knob(s) to the appropriate CC lane(s) in cubasis (the one with the same CC number as the knob sends). After all, the knobs for filters, envelopes, osc-modes etc. on most interapp synths are not nomally advanced MIDI (like sysex) but just simple CC’s that could be recorded. (That is: actually I only know what they r e c e i v e - see for an example the iMS 20 MIDImap, attached below - not what they send - if anything?)
So maybe the problem is, that the app only r e c e i v e s MIDI CC, not transmits it?. If so, it would not be possible to record the actual knob-move (but maybe go further, and extend the interapp-standard to claim s e n d i n g CC’s to fully comply)?
If the problem is missing transmission of CCs in some apps (synths), maybe someone could point me to a synth app, that actually t r a n s m i t CCs (so far I have tried Sunrizer, iMS20, iMINI, iSEM, iPolySix, with no luck)
Hope you see what I mean - a bit hard to explain in short 
iMS20 synth MIDI Map: MIDI Control Chart
PS.: finding the CC in the map and drawing in the apropriate lane in Cubasis is working, which confirms that the controller knob in the app, actually recieves the “move” (actually - maybe not surprisingly - it is animating the drawings by “turning” the knob at play back.)
Best regards