correction of diagram; more accurate

Thinking about a 500x500 corexyu IDEX; but was worried about belt length and squareness. I noticed craftbot has different kinematics, which I think would address at least the squareness concern and some belt length. It has a markforge like resemblance but not the same. Wonder if this can be accomplished with the duet?

thanks;
trying to avoid marlin; like to possible upgrade to E3D tool changer in the future.

picture enclosed. 1 stepper for Y movement; but the two stepper are stationary like corexy (reducing weight on y gantry), but need to account not only for x movement but also add in y movement (X+y)