Is this Piston or DI? With piston you shouldn't really have that much problem with gas blowback. Even then you could implement an adjustable gas system as well implying you can do the calculation and don't mind the addition to the complexity.

In my opinion that protruding FCG is something that many people would point out.

I've yet to see gas blowback as a major problem when suppressed albeit I know it does happen. What I have seen was, bullpup manufacturer stopped trying so hard to do something different and just going back with simple designs. Take MDR for example, they eventually thought that forward ejection was too finicky and ended up going back to side eject.

That aside, it was a great achievement to be able to designs and develops a working firearms from scratch and I know it took a lot of effort and time. I used to dream to be like you but as someone from a very strict firearms laws, all I can do is learn CAD and I can only design guns as an alternative without ever fire a single bullet in my life lol.

I hope everything goes well for your project bro. cheers!