A solution was found!
In Cubase 5, in order for NRPNs to work, the 4th bit flag should have been enabled in the generic remote (seen in the XML). In Cubase 7, it seems the NRPN bit is the 5th bit, while the 4th bit is… soft takeover!
Why is this hidden from users I don’t know, but it’s great news for me not wanting the takeover, and others who do want the takeover.