Gonna be honest, I've watched the old timers in my area try that adobe trick and it did not hold up the same way for everyone. Part of the problem is that adobe mud mix depends a lot on your local dirt, and what works in the North Valley soil might behave totally different two miles away. The wet tarp thing is real though, that slow cure is what keeps it from cracking out on you. My take is it works great on old plaster and adobe walls but you get in trouble when you slap it over newer drywall or painted surfaces, the stuff needs to breathe or it just pops off.

My Roma plant did something similar after we got a weird cold week back in May, and what helped me was just watching the new growth for a bit instead of panicking. The lumpy fruit was the only one that came out strange, and the rest of the tomatoes on the plant ripened up normal and tasted fine all season. Keep an eye on any new flowers and toss anything that looks off, but the plant itself is probably okay.