Benext Energy Switch detected as thing type unknown device

You just need to upgrade the zwave binding to a snapshot version. Lately there have been mixed results using the script.

Zigbee and Z-Wave manual install script - Tutorials & Examples - openHAB Community

There are manual instructions are in the README but basically, you uninstall the zwave binding and place the snapshot jar file in the addons directory. OH automatically installs it but is does not appear ih the UI list of installed bindings. be sure to remove the manually installed addon & add the binding back before upgrading OH.

This appears to be the best link for the latest OH 3.1.0 snapshot.
https://ci.openhab.org/job/openHAB-ZWave/lastSuccessfulBuild/artifact/target/org.openhab.binding.zwave-3.1.0-SNAPSHOT.jar

EDIT: Please stand by. It appears the latest OH 3 snapshots are incompatible with OH 3.0.x

EDIT2: 3.0.2 will be released in 2 weeks. I do not know at this time whether the compatibility will be resolved.