End of the problem: I recovered my RISES.
In fact, the RISE support (MCVenture) had responded to my first ticket and this mail was lost despite my research (I found it later, during a different second search, weeks later).
My apologies for that.
In this email was explained the procedure to recover my unswapped RISEs.
I did it and once I made contact with MCVenture things were very fast.
Thanks to MCVenture, to the team, long life to the RISE project.