People from Iran are very prickly about usages of the words "Iran" and "Persia". They tend to view it as a political decision which one is used, which of course means some folk insist it is "Iran" and others (typically exiles) insist it is "Persia". This can make things quite difficult for the rest of us, who are just trying to classify things sensibly.
I'm not entirely sure what the answer to that is, but I do know that we really need to be using the terms that are commonplace in the English-speaking world. For the country before the 1979 revolution, that is Persia.
When and if they manage to get the rest of the English-speaking world to refer to earlier political entities there as "Ancient Iran", then of course we will follow suit.
So I think you are doing the right thing.
It would seem reasonable to set up ancient-iran as a synonym. Perhaps that's what they are taught the proper term is in their English classes in Iran, so that's what they would expect to be able to search on. We have multiple Iranian contributors, so it only makes sense to be as accommodating as we reasonably can be.