They'd'n'tve
Apostrophe mistakes aside, no native speaker would stack contractions like this. There’s an upper limit of three words in a single contracted form. It would be “They wouldn’t’ve gotten” or “They’d not’ve gotten.”
ML tools don’t write grammatically correct complex sentences precisely because their training sets contain too many discrepancies. They may learn how to apply prescriptive rules consistently one day, perhaps even one day soon, but this is not that day.