At this point of programming I do all my experiences with just a single driver connected to the TMC 428 controller, so that I would expect that all the response messages would be the same.
I did my layout in this order:
1. Micro controller who does the setup work like LUT and this kind of stuff, and also serves as protocol translator for the communication between PC and TMC428.
2. The TMC428 controller who is just connected to a single driver output.
3. The TMC246A driver
The Micro controller and the TMC428 are both at one PCB, the driver at a separated one. So that the only difference between these three boards is just the IC itself.
Any further ideas?