I'm a fast learner?
No. A fast learner would understand that this is the Ottoman Empire and things are more Turkish than European. Your architect is merely reminding you that you don't have a lawyer. If you had a lawyer you would have made the payments through him and he would have ensured that the architect made no funny business. You assume that the architect is stitching you up - perhaps there really are other fees that needed covering or his English was not as good as you thought. Ultimately, do you want to have a house or not? If you want it, five years down the line this will be just one of many minor potholes on the road and in ten years an amusing after dinner anecdote. If you try and build a house remotely anywhere on the planet (apart from perhaps Germany) you're going to run into this.
Fly to Bulgaria, get a local lawyer, get the architect in a room and ensure everything is cleared up and all costs are explicitly detailed. Get it in writing in a contract.