I think there certainly would have been a distinction, since even vulgar English, with its much more limited grammar, has education/class distinctions in how grammar is applied.

In many English communities, using the subjunctive case would mark the speaker as being "posh," as would using I/me/my "correctly" ("me and me gran had supper").

I think the average uneducated citizen would similarly note someone as "posh" if they heard them using the pluperfect subjunctive, and, unlike a modern English speaker who has been immersed in "correct" English through the ever-present media of today, they might not actually understand the sense correctly.