I think H-Seifuku is weaker than C and F, but that doesn't necessarily make her a bad char.
H-Seifuku has some cool stuff that nets low-ish damage and ends in oki. My main problem with the character is that her normals are garbage. She doesn't even have any good specials to help her out in neutral either so you're kind of just forced to rely on her (godlike) dash.
I haven't played her in a while but I'm pretty sure the bnbs I ran were:
->2a 5b 5c 5a 6aa 22a 2c 22a 214a
->2a 5b 5c 2c 6c j.bc dj.BEj.C j.214a land j.bc dj.BEj.C slight delay j.214A
The first bnb sets up meaty pillar and lets you run high/low/cmd grab mixup. The second bnb gives much more corner carry and sets up meaty air pillar. Unfortunately her oki is much weaker compared to C's oki which is similar because C gets 2-3 pillars worth of blockstun to work with, whereas H sets up only 1. Just remember when doing the second combo to delay the last pillar so it is timed meaty.
Basically all of this. When I play H-Seifuku, I don't really feel 22A loops are worth it, nor are the character specific stuff unless you really like being flashy. Maybe if her 2C hit a tiny bit higher they'd work on everyone making it better but... just my opinion. I just basically use the latter combo. More specifics on it:
I like to do stuff into 2C 6C 6B jBC djBE_C (slight delay) dj214A(214B if you are midscreen, change as appropriate) land jBC djBE_C whiff jA j214A (right before you land).
Best timing to do the first j214A is right as you hear or right before the first bounce when they get ground slammed. Also, when you do flame pillar oki, you can sorta do the same jBE_C mixup C-Seifuku has, although its more gimmicky probably. Would go something like:
combo > whiff jA 214A land j9 slight delay > deep(ish) jBE_C > (whiff) jB 5A > stuff. If the jBE_C catches a jumpout, your jB will catch them after the second bounce and you can followup with 5C jBC djBE_C into oki again. If you decide to whiff jB, that's for your low post-jBE_C, and don't whiff for the high option. You can also try to tick by doing jA instead and going into command grab, which will mostly carry back to opposite corner.
Overall, it's what everyone has been saying - she's basically a weaker C-Seifuku with not-so-good neutral and normals. her pressure is a bit more OK with 22 series imo but take that with a grain of salt.
Stuff you can do with meter is kinda the same but it really won't extend your damage - the only real time to do it is to manage your meter. You can do stuff like whatever into 2C 6C (6B) 236C sj9 jBC djBE_C > whatever.
Also, when doing this combo close to the corner, you probably want to do your double jumps straight up or you risk having your flame pillars whiff as they'll come up behind the corner, so you won't always get a forced block or relaunch.