It's like this when canbus adapters are used with the PX5/PX6 when I was playing with them. The software is only able to remap controls when they are fed into the analog inputs, i.e., "key1" and "key2". Maybe something's changed since then. I don't know if other head unit platforms have software for remapping canbus, but you'll likely be waiting a long time if you need it.
There are ways to work around this. If your car has the three wire analog interface for the steering controls, connect them to "key1," "key2," and ground on your cable harness. I don't know what you need to configure to ignore the canbus signals in the TS10 (if anything).
If you MUST use canbus for whatever reason, an Axxess ASWC-1 will accept canbus and convert it to an analog control. They can cost upwards of 100USD. But there are equivalent boxes from other vendors which run a little cheaper. Just need to make sure your make/model is supported. These were made originally to interface digital SWC controls to head units from Pioneer, Sony, etc. which have analog inputs. But no reason why you can't interface with the TS10 in this manner. And afterwards remap the controls.