This is a good point however, very little if anything when Angela take Roland's limbs has any implications that she does it physically. Which in that circumstance means one of a few things like
1. That Angela is physically superior to Roland to the point that he could not defend himself in any meaningful way
2. That Angela can just remove limbs from people by unspecified ways
It's a running thing that the only reason (other than morals I guess) the guests to just die like Roland would have is for Light gathering and in full honestly there is fair amount of information that supports the fact that this kind of teleportation is a thing that can happen rather than against.
At any rate human (which in terms of "power" is quite possibly her at her weakest hilariously enough, depends on how much Light actually matters to her really) Angela can still fight all of the Sephirah and win. As far as I understand it they were properly alive, and thus she couldn't just book them (no more than anyone else anyway). Admittedly only two of the Sephirah are really combatants on a level that would matter in this situation.
My primary point is really that fighting Angela in the Library is like asking to die no matter who or what you are, and the Head reception only makes sense when you think of it at an angle of information gathering, because getting out of the City happens from the outside, and thus isn't going to be stopped and the Head literally can't kill Angela, or force a fight with her, even if logically speaking she would probably kick their ass.