Great work on the DIY Zakki Sieve. You certainly didn't skimp on the thickness of the acrylic
That was going to be the biggest weak link in your design but it looks like you settled on 1" or more thick acrylic so you should have only minimal deflection. Wood coated in epoxy is much stiffer and acrylic so I am not surprised you didn't get much deflection in the walls. If you can keep your system as low head as possible on the suction side then I think you will be fine.
Can you show some more detail on the flange connection for your bottom drains? It looks like the only adhesion point between the corian and pvc fitting is at the top rim of the fitting. You have a CNC so I am guessing you machined out a ring around the corian so it can nest inside the fitting, like a pipe would, so you have more surface area to glue to right? Either way, be very careful when placing the BD and connecting the liner as that joint will be the weak link in that construction.
The sieve screen itself can handle more than 4500 GPH, but the internal framing of the Zakki Sieve is the weak link. Just like in your video, if the water gets flowing too fast it creates a lot of turbulence and some water jumps over the sidewalls of the sieve. That allows waste to bypass the screen. A single 2" inlet pipe will have a max flow rate of 4000 GPH before water starts jumping over the screen. Two 2" inlets should slow things down enough so you can get to 4500+ without bypassing the screen.