I tried CoCo parent set; with "Crazy Painter.CAS". Typing "cload" or "cloadm", a black rectangle with seemingly random letters and numbers appears, then disappears and a message "IO error" appears.

Crazy Painter.CAS seems to work for me with the cocoe (Extended BASIC 1.0) driver
But I am not a expert and Robert can give you more details, I think.

About the cartridges, did you read the softwarelist (coco_cart.xml)?