So I've started a new campaign with 3.2 and I must say I'm impressed with what you've done in regards to the AI attacking and expanding. The WRE is actually holding its ground and the Sassanids (& co.) are taking territory and attacking the ERE a fair bit. You've really done wonders with them actually attacking defended settlements too, no longer does the AI raid your lands endlessly while never besieging. They come for you and try to kill you like they should.
Only qualm at the moment seems to be hordes, the lack of razing really seems to be hurting them when it comes to defeating their enemies. They raid a lot and sack plenty but they never seem to make much impact as the enemy keeps all its lands and eventually they get wiped out. The Visigoths in Greece were a decent example, they just kinda raided the area (and razed one village) for about 20 odd turns until the ERE managed to build enough armies to kill them off, when they died it was like they'd never been there. In vanilla they'll burn the place to ground, crippling the ERE's territory and income. Having them do that again would be good I think, making razing rare means they really aren't a threat because they rarely occupy and at worst they liberate a faction which is easily beaten or subjugated.
Besides the razing they seem to be better, the Huns new army system definitely seems to be working better from a siege perspective.
I must say though overall you've fixed a lot of the issues I've had with Attila since launch. It's actually playable now for one thing. Comparing your progress to the official patchs is quite funny, they've done very little and you've done all this, they should hire you