Its better than most of anything I turn out LOL.
I can follow a schematic but probably not the best person to fully understand.
However..
Just wondering if there is a reason no ground is used on the other side of the level converter.
And why GND on the MKR goes to VCC on the second 7221 rather than being tied to a common ground back to the MKR
Added common ground and cut VCC trace and ran to a near VCC point.
I think it looks better.