Hey buddy, your looking at this all wrong. No need to heat treat if its only a little out of whack. You should pike the bow enough to be able to leave the fades alone and tiller the now stiffer mid to outer limbs only to bring it back around. If the heat treat is still needed, do it very slowly. That way, less temperature is needed, and the glue is less likely to be hurt. You could also try a wet sponge a few times on the area to keep temp on the glue itself under control.
Another neat trick that deserves its own paragraph is dont heat treat the entire width on the damaged section. In the picture you provided, only heat the right side of the limb and leave the other side alone. You can get enough of the wood stiff enough to actually completely unload that damaged area of compression stress, just by tempering to the outside of that area only. It wont twist on you either when you draw it, its too wide there for that... Good luck!