I just want to confirm that I can see the top of my library while resolving Tainted Pact when I have Bolas's Citadel on the battlefield. Is that correct?
These are the relevant rulings:
Bolas’s Citadel lets you look at the top card of your library whenever you want (with one restriction—see below), even if you don’t have priority. This action doesn’t use the stack. Knowing what that card is becomes part of the information you have access to, just like you can look at the cards in your hand.
(2019-05-03)
If the top card of your library changes while you’re casting a spell, playing a land, or activating an ability, you can’t look at the new top card until you finish doing so. This means that if you cast the top card of your library, you can’t look at the next one until you’re done paying for that spell.
(2019-05-03)
In general, if you control Bolas's Citadel, you may look at the top card of your library while a spell or ability is resolving, among other moments. The second ruling you cite mentions a limited exception that applies when "the top card of your library changes while you're casting a spell ... or activating an ability" (a notable example is drawing a card due to Chromatic Sphere while casting a spell) (C.R. 401.5), which can't occur while Tainted Pact is resolving. See also this thread.
These are the relevant rulings: