Better news. I solved the problem with not being able to learn after the factory reset. The problem seems to have been that with the first learning cycles the Somfy roller shutter motors had memorized the io ID of the KLF 200 and then no longer responded to a new learning attempt from the KLF 200, which resulted in the messages of no new product being found that I saw. For the record and others to fix the same problem should they run into it, the solution was to reset the Somfy roller shutter motors to factory settings, the guy here explains this process very well:
https://www.youtube.com/watch?v=sPJsDK2htGs
Then you need to re-program each individual roller shutter again from scratch, again explained very well by the same guy:
https://www.youtube.com/watch?v=bZNUSvfCrD4
After this process was done, I was again able to learn the roller shutter motors using the KLF 200 web interface and also record programs (which in my [English] interface are called programs, not scenes). I can thus confirm that, yes, the KLF 200 is able to learn and control Somfy io roller shutters (the latter so far with the KLF 200 local web interface). Interestingly, Velux themselves tells us on their website that, in order to control their products via an app, we should buy a Somfy TaHoma Connect box (which means for me that io products are and have to be compatible with each other, across companies):
https://www.velux.com/products/home-automation#io_homecontrol
At this point I have been able to confirm points (1) to (4) from my February 16 post, with the small constraint that for (4), one can only run pre-recorded programs/scenes, but one can record as many programs as needed and each roller shutter can be in multiple programs, so that one can have programs for individual roller shutters and programs that combine multiple roller shutters. Sorry for being so verbose, but I wish I had found a detailed description before and from other posts in this thread it seems that others are looking for the same information.
Now I am trying to integrate the bridge into my OpenHAB 2.2 installation (point (5) from the February 16 post). The straightforward approach did not quite work yet, I will keep you updated. Anyway, thanks to all who helped me along so far, it’s really nice to get such good support!
Tobias