I think ComplxNum requires NEON, so checking for the first should be enough.
There is quite a lot of debug message left here. I assume it will be removed in the final version?
These don't need to be in a "ComplexArithmetic" directory - they are already easy to identify from the file prefix.
Can you try and clean up these newlines too. There are gaps in places, but some of the functions are a little jammed together.