Hi Mattia,
This synth is super nice! I am really enjoying playing and exploring it. Very beautiful construction and such a lot of work, and the sound is really VERY korg 
Here are some things I do not understand, and some suggestion:
drum sequencer - I could use a little explanation here, I am confused as to some functionalities between the sequencer and the drum machine. In general, but in particular:
'giro' - means loop in italian, I think? but it doesn't seem to change the behavior here as far as I can tell..what does that do? I am looking at the patch, as well as the synth itself and listening, but I am not feeling very enlightened 
number box/'write'/'clear' at first I thought that the number box could possibly be used to store separate sequences that one might play in, but then I realized that as one 'writes' notes in it simply counts down the remaining steps, is that correct?
the steps one writes to in the sequencer do not seem to remain the same when played back (for example, you might clearly write a note to the first group of four, but upon playing back it is heard in the third group
one suggestion would be that if one cannot save sequences and play back, it might be really useful to simply have a way of toggling the instruments on and off in the drum synth itself, that way you could program a pattern for each instrument and drop them in and out as you play, giving a little more variety
another question -what is the function of the row of radio buttons across the top of the drum sequencer? From the patch it looks like its for setting the max number of beats in the rhythmic cycle, but it doesn't seem to function (it doesn't loop at that point) though if I have the patch open it does 'bang' at the point indicated by the radio box
I am really excited to get a little time to map some cc onto the pitch knobs!
wonderful work!
J