Hi @piattica - I’m not sure what you’re asking for - Aeolus is one of the pipe organ oriented synths on default Zynthian, and I think it ignores midi velocity anyway. Perhaps you can explain a bit more about what you are trying to do.
A search on “aeolus” will also get you quite a lot of related discussion about how Aeolus works.
Here’s the thread where Aeolus started on Zynthian, note that this is historical, now it is just there in Zynthian: