I reinstalled everything and did some more testing.
Everything seems fine, and the SR system is looking pretty cool and balanced so far. I can confirm that Aoe Dflection is working, after all. But it's not working on clouds-type spells as you mentionned (fine for me). More interestingly, the simulacrum of my toon couldn't buff me through it, curiously enough. He couldn't hit me with a skull trap either. It's actually a good thing imho.
I noticed a few things that maybe bugs (not sure where i can post this so i'll write them here for now).
- the Clairvoyance spell (3rtd level) doesn't seem to work, visually at least. When it is cast, an icon briefly appears on the avatar's image then disappears. So now there is no icon, and none of the stats are modified in character's sheet (AC and save vs breath should have modifiers). Not sure if it's silently working or really bugged.
- the dispelling screen memorized on a spell trigger doesn't seem to work. Well, i 'm not sure again, because we have access to all the standards replicates of the classic Immunity spell. There is no text in the trigger's screen for these spells, and there is no way to know if it's working and most importantly which "immunity" version you should choose.