I don't think any sort of test is needed. As long as the device is not being used a repeater for multiple other devices then it could be safely re-paired as LR with no reason to go back.
How to Convert device from Mesh to LR
Scan device into SmartStart via Mobile App
Use this app to check settings (set to Long Range boot mode)
Create Virtual device and swap apps to save your automations from breaking
Alt: you can also rename the DNI to preserve the device entry after exclusion
Open live logs in new tab to watch for pairing info
Exclude device, removing z-wave node, and device if using Virtual Device method
Device should re-pair by itself (as LR) shortly after it resets and boots back up
You can confirm LR mode in Z-Wave details or in my app to the right side on the list
Swap apps from virtual (or old device) over to new device