Sorry to hear that someone else is suffering through a deadline on the updating (Apple Big Sur and InDesign2021) when it comes to using a "Signature" Minion Expert Family that we most likely paid a lot of money for back in the day. My font family dates back to 1987— but so far I have been able to work with updates.
I have tried all the uninstall/reinstall of Minion [Ornaments] to no avail. But I can save some of the placements by going to another type supplier. What I cannot do, even with the new variable system, is save the Swash effects. So what am I supposed to tell a client about missed deadlines? Whom should I bill for hours of hard work replacing a work around? Or, the cost of re-ripping a whole PDF instead of just replacing one or two pages on a standing reprint?