Well, one part of your question is "easy" to answer!

Gravity waves propagate through the space-time continuum.

If the space-time continuum is curved or bent, then they travel that curved or bent path, just like light.

So ya, basically gravity waves can't just magically say, "Look: that 'medium' we are travelling through is bent/curved, let's magically exit the medium, and then re-enter it where it is not curved!"

NEXT... another part of your question is likewise "easy" to answer.

Essentially: a gravity wave, and a gravitational force are not the same 2 things.

I suppose a metaphor might be: a radio transmitter, and radio waves are not the same thing! The radio transmitter is left behind, when the radio waves propagate outward.

Thus you can think of a gravity wave as a kind of pulse of energy released by a "gravity transmitter", in which that pulse ripples outward in a distortion wave of the space-time continuum.

Meanwhile, the actual gravitational source itself, that transmitted this rippling distortion, remains left behind.

ALSO: If the gravitational-ripple-pulse passes into a black hole, then like anything else, it will be absorbed by that black hole, and won't escape it.

I suppose another stretched metaphor (pun intended!) might be: if pull the plug on your bathtube-water, and a wave passes near the swirling drainage vortex, then that wave is going down the drain!

And FINALLY... The other part of your question is INSANELY more difficult to answer... !

(Assuming I even got the "easy" parts of your question above correct and didn't mangle it too badly with bad metaphors!)

The last part of your question seems to ask: how does a black hole exert gravity/influence on the universe, if nothing can escape the interior of a black hole?

One of the answers to that question is that the value of a black hole's gravity, and even electrical charge, is imprinted upon the event horizon. From our point of view, of our limited human life span, nothing seems to fully cross the event horizon. It just gets slower and slower and seemingly more "frozen in time" the closer it gets to the event horizon. So that information can still sorta be "seen" by us and the universe, and still has effect upon us (since it's not yet on the other side of the black hole).

But of course wait around trillions upon trillions of years and those things eventually cross over.

In the meantime:

From the point of view of that thing approaching the event horizon however, it crosses over IMMEDIATELY. So for example, if it was a person, they wouldn't notice in their own mind that their brain's processing speed, and thinking speed became slowed from our observational perspective almost down to zero.

So the value of charge/mass is in that way kind of frozen/trapped/imprinted, or whatever at the event horizon, thus a charged field can still happen, and a gravitational "field" can still happen, since that information is "visible" and knowable.

And ya... CAUTION:

My last explanation might have gotten some of the idea wrong, and I'm really hazy on it, and it shows.

So someone else here may be able to make corrections to my explanation and give better metaphors or visualization of what's happening (which supposedly is kinda tough to do without some mathematics).