Indeed, if it would be easy more people would be throwing around custom mgs like that. But no one is doing that because it is no easy feat.
These animations are difficult to do, so they aren't worthy because what we have works fine and even if it doesn't, we would need to make sure it does instead of going forward to create something we aren't sure we will finish.
I am grateful for the existence of the SG-43, because if it didn't exist, Soviets wouldn't be having a HMG in their ranks (or perhaps would be using a retextured version of CW/US). That difficult is for everyone to create a different one.