Thanks for your detailed explanation that raised few more questions :
You wrote you used also Misumi linear bushings but in you BOM their links refer to Robotdigg website.
Did you get Misumi linear bushings from them ?
Or you BOM is not correct ?
Coz LM6LUU or LMK12LUU are not Misumi references but more Aliexpress or THK references, i found for the real Misumi respectively something like xLMUWx6 or xLHFRWx12.