I'd agree. And getting punished for a baited Thresher is one thing. Getting punished for an HI that could have reversed as a Thresher is another thing.
Ultimately, while I would prefer an input change so there's no ambiguity whatsoever, it is merely a quality of life change that isn't a deal breaker by any means.
Also, what is throw start up? 7 right? I was getting throw a lot trying to see if blocked hk.pinion > HI was punishable by a throw. I teched it a few times, but usually got thrown by a dummy set to mash throw as a reversal. It is frame perfect I'm guessing?
Throw startup is 7, meaning you need to be -8 or worse to get punished. Pinion to HI is -5, because Pinion has some weird blockstun that lets them move like 8f before Painwheel, I really should fix that.
But anyway, -5 is not punishable by a throw or Fortune's s.LP or anything I remember offhand except SSJ.
Here's a key example why the cooldown hurts Fukua's game.......Lets say the other player jumps and is met with a ground H fireball from fukua and its blocked. The other player now has time to close the gap with little worry of another fireball. Fukua doesn't exactly shine at close range so her best bet would be to somehow get back into C.HP range. You could argue that you could use a shadow after the blocked fireball but all of those are too slow and can be punished (primarily to jumping attacks).
This is a better answer than I expected! I do wish you had posted it a while ago instead of doing all that junk first.
(Fukua does have other tools to use in the holes, as other people have ungracefully pointed out, but that's not the point of this inquiry so I'm gonna ignore shadows to begin with.)
Let's take a look!
At round-start positions (1/2 screen), if the opponent jumps into an HP fireball, the wraith returns 4 frames after Fukua recovers, so you aren't really losing a lot. You are also +6, so you can start the next fireball 2f before they can move again, and it will come out 11f after that, which is too fast for anyone to reach you and stuff it, even a lowest chicken-blocked Filia dash cr.HP.
At round-start plus one Filia backdash (3/4 screen), if the opponent jumps into an HP fireball, the wraith returns 24 frames after Fukua recovers, and you are +18. That means you can throw a fireball 6f after they can move again. Fireball startup is 13f so that's still not too bad, your next fireball comes out at 19f and at that distance it takes Filia 25f just to wavedash to you.
At round-start plus two Filia backdashes (fullscreen), HP fireball is no longer anti-jump because they will jump over it.
It does indeed affect her fireball->fireball at about 3/4 screen, requiring you to wait about 24 additional frames. You're correct.
Now, to see if that truly breaks her zoning game or just requires a change of plan, let's un-ignore shadows.
At round-start, if you throw an M shadow after the blocked HP fireball, Filia can dash in and hit you before it reaches her. However, if you throw another fireball, it will reach her before she can hit you.
At round-start plus one Filia backdash, if you throw an M shadow after the blocked fireball, the shadow appears as the wraith returns to you, and is active and out on the screen 8f after Filia gets to move. As mentioned, she can't reach you for at least 25 frames, so here a shadow is completely safe from further advance and requires them to dodge or block it. M shadow at that range has Fukua recovering before it even goes active with an advantage of 35f at minimum, and the wraith has already returned, so you are free to throw another fireball any time and be at huge advantage for it. You can even back up to get more space first.
At round-start plus two Filia backdashes, which is just outside the range of M shadow, the same applies because you can begin another fireball before the M shadow goes active.
So my conclusion is forced to be, based on empirical evidence, that although the change affects fireball->fireball specifically, at close range you can throw another fireball with pretty much no delay, and at midrange she has another
unpunishable viable zoning tactic that allows you to keep the opponent out just as effectively.
?