Couple of things to clarify here, Adam. The anti-parallel diode across IGBTs is a totally separate device, not intrinsic to the structure as it is in MOSFETs. In both devices, though, the anti-parallel diode is eminently suited to being used as a freewheeling diode, it just needs to be in the proper location, is all
Yeah, those capacitors look really shaky. And the high inductance pathway between them and the modules isn't good, either, but until the circuit gets sorted out it's still a bit premature to worry about "details" like these....