Could you send the complete error log. NUM_AXIS is used at a lot of places in the firmware and it’s a bit hard to pin point the issue.
You might be interested in getting Marlin-RC version instead of Mjrice build for your Wilson RS as it doesn’t have the added code that is needed for Wilson 2 (rack and pinion Z probe, etc…)
Here’s the “Classic” Marlin-RC firmware : https://github.com/MarlinFirmware/Marlin/tree/RC
You should check Mjrice Wilson TS original build video for the configuration setup.
Hope this help.