Try not to get there in the first place. Like I said many times Chun has weird matchups and in certain spaces an advantage matchup can turn ugly. REALLY, REALLY UGLY. She doesn’t have as good of get out of jail cards as you think she would. You kinda have to work your way out.
Otherwise try legs or something. You can attempt a tensho or buffer legs duing blockstun to try to push your way out. Don’t be afraid to counter throw either. This game has reverse ticks. Also there are certain moves chicken wing can lose to easily. I don’t play vs fei much so I’m not a super expert here. Try legs, try the really fast pokes like st lk/mk or tensho. Super should work, and I suggest building meter really quickly in case you get locked down. Chun can do some really neat things with super. Ever seen DJ dread kicks>super? Chun can do that near the corner.
Also it would help to look at the frame/hitbox data comparison site that I believe you posted on here originally. Either you or pasky.
Some chun super tricks that I was going to post up
Cmk to super- does not combo often. Walk forward super motion, down mk very quickly, then very quickly negative edge forward k or press forward k.
Fireball> Cmk> super: Do back, forward P, back, hold forward to follow the fireball, then connect with a cmk using the above trick and super, can follow up with upkicks.
Crossing up or being crossed up and supering> Switch charge directions with specific timing. From the wiki,
The most damaging meterless combo/un-combo thing ever: J hk> hk legs. 75 percent, stuns. Good luck landing it though.
stand at your opponent’s max poke range and mash some legs. builds meter, if you are a bit close they proximity block, which sets up a throw, and from max range most pokes won’t go into her uh… weak spot.
st lk is good. better than you would think. beats a lot of stuff that it has no right to beat.