No see, Corypheus is what implies that the Architect is a magister.
How the similarity between the two fail to make this obvious to some people is...astounding.
Not at all. The point remains that if indeed The Architect IS a Magister it would be a bit of a retcon, and certainly is not yet canon (having not been stated in any tie-in product or game).
They may seem similar, but no part of The Architect's story to date even mentions his being from Tevinter. He is only ever refered to as being a Darkspawn who realise he was not like other Darkspawn, in as much as he was not slave to the calls of the Old Gods and could make other Darkspawn the same.
It has all been kept very vague. I had figured intentionally so.
The only true similarity we know of between Corypheus and The Architect is that they are both intelligent Darkspawn, capable of formulating plans. Corypheus wants to restore Tevinter to and the Old Gods to Glory, The Architect wants to end conflict. In particular by ending Blights, and the Old Gods' control over Darkspawn, and the Taint.