I assume its a Ford ESP factory warranty they are offering? I have seen dealers in these situations provide an aftermarket 3rd party warranty. Not acceptable.
It sounds like the extended warranty (ESP) adds 75k miles to the mileage you already have accumulated which is 14k = 89k miles. This is how extended warrantys work. Features in the warranty cover "progressively" and "kick in" as factory warrantys expire. Sounds like you will also get 2 more years of coverage on the Powertrain and 4 more years on some of the B2B items. So, you are not actually getting an additonal 75k of warranty but only 61k on SOME B2B items (factory BTB expires 36k) and only 29k miles additional coverage beyond the factory powertrain warranty (your trans) that expires at 60k. Ford should offer more but they don't HAVE to give you or honor anything except the warranty that came with the car which you paid for. Factory warrantys are part of the purchase price and cost to produce a vehicle.
But, there is added value especially for the B2B items cause it covers things like A/C, cooling, fuel, electrical, entertainment, (not trim, interior pieces and lots of other stuff). Carefully read the warranty contract (not the brochure) and focus on "what is not covered". Your best warranty is called an "Exclusionary" warranty and typically is the highest level of whats offered E.g. "Platinum" level vs Silver or Gold. There is also added value if the warranty is transferrable to the next owner if you sell it. It should be but I'm not sure. If a $ amount will be assigned to the warranty I'm also not sure who is entitled to a refund for any unused portion of the warranty, Ford or you the owner? Maybe Ford because they are paying but you never know as the warranty will be in your name. Again, find out f there is a $ or value amount to the warranty. All questions to ask.
Rebuild of repair the trans? As a Master Tech, all I can say is I can't say for sure. Like any workplace, some employees are better than others so for a rebuild, if the technician at the dealership is good, you'll get a good working trans. Theoretically, the New Trans, should have all the updates and corrections done and built at the factory (not that they got it right the first time)

but we hope the new factory replacements are better.
Sorry for the long rant, but I feel your pain. I'm not a knee-jerk "get 'em to buy it back" guy but if you feel enough is enough then I would explore a lemon law case with an attorney and not the internet or your state government only. Others have said they just traded theirs in and got a different vehicle. If you can afford the loss, then sometimes it can be cheaper to get rid of it, take the loss and go make money however you do because if you're don't, that cost you more money. Figuring sales tax, depreciation and fees, it would be about at least $10k hit to switch vehicles. Some manufacturers like Ford will do a cash settlement vs buy back and you keep the vehicle with a clean title and full warranty. I've done both in my years and each has its pros and cons.