Several things here. The US did refused to call Rwanda a genocide. This was right after the Rangers debacle in Somalia and the US was in no mood to support another disaster.
UN Bureaucrats, more specifically Kofi Annan, were responsible for countermanding the Ground Force Commander, then Major-General Romeo Dallaire, and not allow him to pre-emptively strike against the genocide consipirators. That would not have changed with a totally dedicated UN Force.
There is the
SHIRBRIG. It's now a joke. The militaries involved want nothing to do with the UN bureaucrats.
When UNIFIL was being bombed, Koffi Annan was on his weekend getaway (his NORMAL weekend getaway). This while every Prime Minister and President on the planet was busy on the phone with Tel Avi arranging safe passage. Both Canada and India as well as others had special forces on the ground in Lebanon finding Canadian and Indian nationals through this arrangement. From what I saw, Koffi Annan was more p!ssed off at cancelling his getaway than about "his" people getting killed.
None of this would change with a dedicated UN force.