well, i've changed something in my data.pak with whinhex about 3 or 4 days ago and i still can play. The incorrect id issue happened to me too... but on another acount that i use only to sell things :) i've write to acclaim support and after some hours all was fixed.
Btw i've changed the autopot, the blow % and some other buffs.
I havn't try yet the change on the skill because i'm doing pk party so the game read others data.pak, but in the old 2moons version i've made attack accelleration wit 99% crit rate and soloing crevice every atk was a crit, so i can think that can work in BMR too.
i've tryed to change the buff for the atk dmg but i can see in the stat page that i had 20.000 atk but the dmg was always the same.