I have only a cursory understanding of this, but my understanding is the "technical" architect is are more hands on, will project manager more and ensure materials are right etc for the stadium. While it's not impossible, I would say it's unlikely they look to massively row back on the original design, they are more in place to ensure the vision gets carried out.
There are lots of reasons for the change. At one end it may just be the club don't feel Meis has the expertise to manage the project having designed it, or that they wanted him to tender for it but he didn't. At the other end, it may be a cost cutting exercise to end up as a mechano type bowl stadium. I would be very surprised if the club allowed for major movement on the Meis design, which was widely popular.
My gut instinct would be, a pressure point may be if there develop cost implications to keep certain aspects of the bespoke nature of the stadia. Thats where a conflict may emerge. I would imagine though, any fundamental shift would be at the behest of the club, as opposed to the architect. I'd be surprised if the club allowed for them to wholly move from the original concept, otherwise it would be pointless engaging Meis in the first instance.
I mean who knows? I think there's plenty of distance left to run on this one. I am sceptical about the stadium, but not for the issue of Dan Meis.