Hmmm, in fact that was just me mis-selecting in the Time Finder. I probably scrolled too hard and my research was made for Roaming Pokemons, which explains why the IV frame was off.
I now have another, more simple problem: is anything advancing your PID Frame at the top of Dragonspiral Tower ? Because I got a flawless Zekrom, but with a nature which is off by 12 frames (and although I'm not superconfident with myself, I think I didn't chatter 46 times instead of 34).
EDIT: Tried to compensate for the 12 frames, but ended with a nature which is not even listed in the PIDRNG list for about 100 frames forward. Lost.