Should they be liable and fix it right ????
Absolutely.
Your generic "COMEBACK" is what is know as I came in the doctor's office stinking like shit. Doctor gives me a breath mint. My nose [oil bag] wasn't dripping so what other 2 holes are left? That's why malpractice insurance is for the inept doctors like inept mechanics [need] the same policy.
So they eat their own job or it's a court date for them, they charge you again? No, that's not how it works. It's own up to your inept diagnostics. It was not solved, the question is why? Groove in shaft? Wrong seal? New old stock seal and it's dry and crack and slipped thru the builder's: eye didn't catch or think about that so it's your fault. No, that's not how it works, that person touching that whole deal is all back on his lap... don't touch it.
Why was not a dye placed in either the mouth or rear end? One was going to fart out the dye, pepper the tranny case with a fling or spit it up you see the primary is dripping and that was just sitting on the side stand at idle. All that tranny oil on that side, they have grandpa's 1960's black light to see the dye shoot out someplace?
Can't be 2 oil leaks or you'd see both colored oils, yes? So do not let them say it's your fault when it came in to 'repair oil leak.' I have no clue where the leak is, that's why I came to you with a sign on your door saying, we fix oil leaks, tire leaks, and compression leaks. And if you can't do it right the first time, who's fault is that?