I am in late night grading jail. Students who have not studied verb forms fully, but who have understood concepts, are deriving from what they do know the ways in which things would in fact have been said in Old Spanish or in the Renaissance. How did they figure out when the future subjunctive would have been used or how to form this? It is extremely interesting. A person with a very systematic imagination could in fact reinvent this.
But in their jobs, are they perhaps working with people who do in fact still use the future subjunctive? I have had a related experience before. Students working with people from New Mexico who speak 18th century Spanish, learn those verb forms (vide for vi, for instance). But now they are writing in yet older forms of Spanish and I am sure they are not plagiarizing. If they have learned to speak this way from living people, where are these people from?
Or again, does language work in such a way that these students, rushing to do homework and not studying the things they should study first, have reinvented Old to Middle Spanish?
Axé.
coldhearted scientist وداد 
that is really fascinating. if you ever figure out how this happened, ie reinventing or learning and from where, please update this post and let us know.
I’m glad I’m not the only one who is tantalized! They swear it is not even reinvention, it is just a few lucky mistakes. I want to think some deep piece of their brains and the language caused them to reinvent it.