Hi,
I’m still learning here, but “level” in this group is for all “level”, “flat” , “square”, “parallel”, “tram”.
So I’d say once your table and base of the machine is level, what is important is that the X linear is parallel to the 2 Y linear modules. Not the top of the Z posts.
After my initial assembly I realized that 1 side was a higher than the other.
@brent113 here had a simple solution to make it parallel. Since I read that and apply this technique it help a lot my prints, cnc and laser. ( BTW, thanks brent113! )
Do this when your machine is OFF. Slowly push down the X rail down to the 1x2x3 blocks or a precision straightedge.
I redo this once in a while just in case.
Cheers