No offense but none of what you said makes any sense. I’m not a Fei or Vega player, but I think I can offer some suggestions, or at the very least I can say something comprehensible.
If Fei wants to pressure Vega while he’s in the corner, he has to worry about Vega’s Scarlet Terror (Flipkick). Fei can beat the Scarlet Terror by jumping on a knocked down Vega very late and very deep into the corner so that he’s touching the wall. This will make the Scarlet Terror whiff or get stuffed by Fei’s jumping Forward, the same as Guile’s Somersault in the corner will whiff against Fei’s deep jump in.
Other than that, the next best option is meaty crouch Short which will make the Scarlet Terror whiff from max range. And then from there Fei can mixup into throw / bait / Flame Kick / Chicken Wing. Using the Rekkas is not very smart cuz Vega’s crouch Strong is very fast and makes any Rekka unsafe from close range, except maybe a meaty Rekka. IDK for sure though.
Of course Vega’s Backflip will avoid everything, but it’s also easily punishable. This is all very basic stuff, and I’m sure some good Fei or Vega players will comment and offer some advanced pressure tactics.