If I read OP right, she expects transactions that occurred more than 30 years ago to result in a Lifetime Platinum designation today. She is counting on that status to deliver room upgrades on imminent trips. The "beyond upset" part is not only because Marriott, like many companies, does not cache masses of customer data from the 1980s, but because OP and husband might have to angle for elite treatment on these upcoming trips based on Lifetime Gold, not Platinum, status.
OP welcomes advice. Mine: life's too short.
I ran up a bunch of Pan Am Worldpass miles in the 1980s. I do not expect Delta to do anything for me today as a result. Especially as in this decade I am an infrequent, zero-loyal Delta customer. I think this situation is not so different.
I am not sure why today's Marriott organization should be savaged for not rewarding stay behavior that occurred in part during Ronald Reagan's first term.