Hi,
The firmware update over UWB will not work from R1 to R2. The main reason is because the UWB Mac layer was modified in the R2 and is not cross compatible with the R1.
In order to flash your R1 modules, you can do it either over SWD or over BLE.
The UWB OTA firmware update can be used to flash a device with a new R2 firmware + user application for example. (But the initial device would have to already run R2)
Yves