I wouldn’t worry too much about Q3s or CDD’s, especially ones that occurred 6 years ago. Having an opportunity to explain a “blemish“ where you learned something can actually be a plus during an interview, So long as it concludes with a positive outcome and that you learned from it. Interviewers aren't expecting everyone to be Roger ramjet perfect candidates.

With SW’s hiring prospects going forward, I suspect fogging a mirror with a wet ATP will qualify. Indefinitely stalled contract, narrow body pay, 10 year upgrades, Lubbock overnights, lost mojo, etc,, combined with very ambitious growth plans, I would imagine you’d be front of the line.

I agree with others that applying at all the majors is highly advisable.