The 5B is tested and fully validated on t2i training. All other models and modes (A14B, i2v, timestep ranges) are tested to confirm they run and that the loss looks reasonable, but proper learning ...
FEX-Emu is an x86 and x86-64 userspace emulator built specifically for ARM64 Linux. This means it helps programs designed for Intel or AMD chips run successfully on hardware using ARM chips.