that version of krona was a complete disappointment in the GL issues, he literally, didn't have any feats, he just stood there and let his minions do the work, then got beaten by a dozen of GLs in the end (of course, as one might expect, he was considered a universal threat, but he didn't do anything in terms of feats). However, he later came back (outside the GL issues) and actually did something, he was able to warp time and space (despite the fact that one of the superheroes claimed he shouldn't have that kind of power, which pretty much indicates that he's not really that powerful).
Time Trapper on the other hand, managed to create a pocket reality - a full blown universe, he was able to warp all timelines simultaneously. Both of these feats are pre-zero hour though, the picture shown in the op is from Legionnaires #61, that version of time trapper isn't any less powerful, he mentioned that he had the ability to create entire realities from a single moment of time (pocket realities, like the one shown in AC 591 for instance, which was pre-ZH) and was threatening all of existence.
Very much so.......first off, you're talking about a different version of Krona, The OP specified the GL/Darkstars entropy incarnation, while you're using the JLA/Avengers version.
btw krona being entropy doesn't mean anything considering the time trapper himself is the embodiment of entropy, LoSH v4 #4 (notice in the same scan he also comments about warping all timelines):