Jannissary in high?

[The Grand Inquisitor]

I modded my build_prod to make make the military academy require a mosque, not a grand mosque, so that I can have more than one province producing them, in case that appeals to you.

It is possible to get more than one province producing JHI without altering the build_prod file.

The Military Academy is not a unique building, though the Grand Mosque is. So once you have built your MA, knock down the GM and rebuild it elsewhere.

But TBH, one province producing a unit of JHI every turn is usually enough.