Shapespark assumes that objects have real-world sizes. If changing the unit in Maya doesn’t change the real-world size of a model, then it’s the expected behavior that the object has the same dimensions in Shapespark no matter if you set Maya to use meters or inches before the FBX export. If you use inches the sofa is imported as having 11in in the real world, and when you use meters it is imported as having 0.28m, and it’s the same real-world size.
So, to change the real-world size you have to scale the model in Maya, not just change the unit.
What do you mean by a bump map problem? Could you share the link to the uploaded scene, so we could take a look at it?