I can not do it anymore, because yesterday I lost patience and I trashed the database of Origin.
This database was originally created by Studio when I tried it two months ago.
After that, I launched Origin again, and it started to import the library of 3.5 without asking me if I want it to do this import. The import lasted a few hours and ended by a crash.
This morning, I had a good idea.
I used Time Machine to restore the old database that was created by Studio as replacement of the database of Origin.
Now, Origin works well again, and I’m happy again.