They told you wrong then. I think I have only transferred once 2E to 2D in more than 85min and usually 65min. Is it nice, no, is it suggested no, but the question was is it legal, yes.
We have all assumed that you are on AF the whole way so please advise if this is not the case. AF7 connecting to AF1618 is the tightest JFK-FRA connection with a legal connection time of 75min.