There isn't an easily accessible resource regarding leixia's aGIs here is there?
The wiki shows it aGI's all weapon attacks (and yet you say it is a limited number of movetypes) as well as leixia retreating backwards (which can limit the options an opponent does). I don't have the frame numbers, but I know that it can handle at least i16 to i20 retaliations.
While the opponent reading either you 44B4 vs 44B, it does limit the number of frames that can be used as reactionary punishment frames, which means the move is safer than "-22" some of the times.
its -2 on block, i15, decent range for i15 move, sends them flying on both NH and CH, and seems to catch steppers reliably. Lots of good leixia properties except damage. I highly doubt you would choose to use 4K as a big fat combo damage dealer as opposed to a low risk poke that can break momentum and cause ambiguity on block.
4A+B beats out all the major 14-frame punishers you might know about. From Alpha's FC3aB, to Mitsurugi's 236B, to Raphael's 236B and even Pyrrha's, Omega's and Pat's 236Bs.
It's also capable of shutting down mid horizontals like Nightmare's 22AA, Astaroth's 44A and others. After a successful aGI, you can CE. Depends on your distance of course. 4A+B also has some evasive properties on it that can make it a useful evade.
Laughing Her Bea Hua, aka the aGI in 44B4, 66B4, etc. Is mainly used to stop verticals. The hitbox is a bit weird, but a successful aGI drags the opponent close enough to Leixia for a throw/mix-up/CE.
4K is basically a punisher that's fast enough to hit someone that decides to step while at a frame disadvantage. For example, you can use it against a Patroklos who decides to 66B then step. 4K will catch. Normally, Leixia's fast punishers are mostly linear. 4K happens to be a fast horizontal punisher against close range targets.
I've decided to move Leixia from bottom-mid to low-tier, though probably an "upper-low" as it were. The main thrust is this: when Leixia fights an opponent, its dangerous for her when she guesses wrong. When an opponent fights Leixia, its not too dangerous when they guess wrong. Combine this with all the flaws and holes in her offense, difficulty getting in and handling back-dashers among other things, she's got nothing major to really show for it.
Sure, you can force your opponent to get a Quake Step GB and then hit them with AA BE. Only by the time Leixia swings that last hit, it will be GI'ed or aGI'ed. Or the opponent blocks and you're at 0-frames against your enemy (an advantage, maybe?) But its a gimmick, and so much of her stuff is riding on gimmicks that won't work against knowledgeable players.
Of course, this is my personal tiering. Feel free to disagree.