@Acku I might have some things you could try.
Generally i I punish ibuki’s Snap Kicks(Tsumuji) with either slide or cr.mp. Slide because if she does 2 your hit box is to low for jab to punish and her knee will either wiff or trade at best. When she does Sanp Kicks she pushs rose back to safe slide range so if it hits attack, if its blocked block(maybe throw if your feelin gutsy). If its 3 kicks it pretty much the same deal but with more fame adavange(if you see three kicks its better to go with this since it wont wiff in most cases) and safety and the possibility of a 1f to cr.mp (ex.kicks is exact distance for the 1f might be a 2f if its spaced right) just watch for her fwd.lk after the 2 kicks it will hit slide. Cr.mp is a safer way of punshing the 2 kicks but will wiff on three unless the poke.(st.mk and st.hk are also options but they are slower and could lead to counter hits from ibuki since most dont use her lows after the snap kicks, cr.mk doesnt cancle,lk. is to short and slide/sweep is kinda unsafe).
If you know he’s going for vortext just block the kunai it can kill Ex.Sspiral(though i did see u get out a coulpe of times, I think your friend just barely mistimed his kunias) along with blocking you can toss in a FA every now and then if your not worried about an option select(i think it safer to just block) so you can escape. Along with blocking keep an eye out for her lk cross up and empty jump to throws most will mix this in after a failed vortex’s.
Her st.lk is good poke 4f start and decent range(is about the same distance as cr.mp or st.mk) and cancles (most of the time to Snap Kick(lk,ex) or Rida, everynow and the to srk kick but thats mostly for a punish on move that ouf of st.mk range) even with that is not as easy to use as cr.mp so dont let it bully you, remeber you can do this from cr.block when ever, they have to give up blocking to use this so pick your spots and toss it out with a bit of tact, if your good at buffing its not bad to buff in a SSprial(mk/hk) or a SSpark.
Capitalize on you knock down, i noticed you gave him a bit of space, dont. Unless you backing up to come right back with SSpiral or slide,st.hk or dash grab (all are kind ofunsafe if the ibuki decides to Kneck Break but most good ones wont do that, but just letting you know the risk). Just stay close and be ready to block if there is Ex. avaliable or c.lmk if they have U1, if they do ex. you can punish the kunai with FADC you could just FA (i dont like to because it can let her get back to neutral postioning.hitbox and speed issues) but do that and then punsih with cr.hpxx or you can use SThrow if you dont execpt a kunai (a slightly delayed Ex.ST should work if they do kunai) and then countinue to pressure in a way ibukiswake up like our’s without U2 but in some ways its slightly worse so take advantage.(OS if they start to back dash)
Watch your Ultra its good but ibuki can hold her own against it (your friend has nuts(I respect that) so he’s looking for a chance to knock it out, sometimes he just gonna guess, either way be a bit more consious to the possiblities) Even though he didnt go for it Ex.Kneck Breaker can be a U2 killer if your not on the look out as well as slide (which u wittnesed). Much like with vortex kunias kill EX.SSprial they can do the same to U2 so pay attention after/before you activate it so you can get to use it, also if he good at Tk and has a full bar watch for supers they can get low enough to touch you toe.Ex.Hien can trade or some time clean beat U2 so dont get to comfy with the Sparks(if your starting the chase trap or if your doing a chip away) between Hien,Kneck Breaker and ibuki’s U2 (9f start up full fireball invinc) you need to be on you toes. U2 should be saved for wake up(watch for kunai) or direct combo’d either from FADC,punish or jumpin/cross up.
Oh you can OS her OH with the Cr.HP OS if he doesn’t use b+lk first. OR you could use Ex.ST if you feel one coming and get big pay off.
Thats all i got hope it helped, also i felt your pain in match 5 at about 3:20 i hate when i FADC and press the button to early and the game just bypasses my cr.mp/hp and SSprial just pops out that shit is annyoing as hell. Got to work on those links try a metronome it helped me ALOT since i dont like trying to plink on a pad.