I mean, my experience with LotV was also that the difficulty of levels somewhat reflected that order. Except the temple on Shakuras, that was hard.
In terms of logically trying to break down the order of HotS, the idea that Kaldir game after Char offends me, and that it came after Zerus offends me again. And then the idea that you get mutas and swarm hosts before roaches is all kinds of unthinkable for me.
If Kerrigan goes the Kaldir first, her beating up on the Protoss makes total sense. The closest she ever came to being friendly with the Protoss was while being the queen of blades, which is not very friendly, so she would have zero issue batting them aside to get some better Zerg.
However, if she goes to Char first we see multiple problems. Firstly, Zagara has hydras, so for Kerrigan to not have hydras and Abathur to not be able to make hydras after reclaiming Zagara doesn’t really make sense. Though, she also has mutas too so to be fair, that would almost put her on char last of the 3. Further, if we are to assume Warfield’s speech had any effect on Kerrigan whatsoever (it looks like we are to assume that from how she reacts), it does not make sense for her to suddenly be genocidal with the Protoss. And finally, if Kerrigan goes to Char first, that means she killed all the Protoss on Kaldir AFTER meeting with Zeratul. There is no more claim of non-collaboration here.
And then after all that, going to Zerus first makes it even worse. Now she worked with Zeratul, going along with him. Now for her to kill the Kaldir Protoss? No way. Also, it makes interaction on Zerus cease to be logical: Abathur gets mad at the primal Zerg for stealing his Hydralisk strain after the swarm was on Zerus for a few hours. However, if you haven’t been to Kaldir yet, you don’t HAVE hydralisk genetic material to steal. It’s not available on the leviathan at all, unless we now go back and start counting Zagara’s hydras now, awful convenient we didn’t before. And if Kerrigan is now the primal queen of blades, her fear of the Golden Armada no longer befits her. She is too arrogant and self confident to fear the Golden Armada once she has a chance of fighting back. We know this. And also, it makes leviathan interactions on Kaldir make less sense. When Kerrigan complains to Abathur about how she thought he made her swarm stronger than this with the swarm being so crippled by the cold. If she just took command over the swarm, this complaint makes sense. But if she has already taken back char and conquered Zerus, and now she’s still complaining? That no longer fits.
There is so much wrong with going to Kaldir last, if that is really the canon order than I lose all faith in blizzard story writing, and HotS was already weak at the best of times.