I only use equilibrium curing for nearly everything now. 2% salt plus cure and the spices you like.
Curing is done in 2 stages. Halve your salts etc and cure for around 9 days, than add the other half of the salt concoction and cure for another 9 days. When curing in a vacuum bag, do change everything into a new bag for the second 9 day cure..
Curing is done in a part vacuumed bag to help the daily massaging and assures no mess
You can even leave the Coppa longer in the cure, no harm done as they will not become saltier.
After about 18 days of curing your Coppa is ready for the UMAi bag no ifs or buts, firm or not.