It’s hardcoded to the info-loglevel here. This indeed could be reduced to the debug-loglevel I guess.
That being said, I personally wouldn’t use info as the global level anyways. If everything is working, it’s fine switching to warning. Other integrations (which you might just not have in use) probably generate a similar amount of messages.
The reason I’m using Info is after a failed attempt at migrating from OZW to Z-WaveJS, I decided to finally wipe my Home Assistant setup as it’s been running since version 0.31 (Oct. 2016) and start afresh.
The logging was useful for troubleshooting as I recreated my setup, but the HomeMatic logging was getting in the way.
Previously, there had been a lot of errors logged about missing entities, etc. Now that new setup is up and running, there is almost nothing logged except HomeMatic, but I would definetly support changing HomeMatic to debug logging by default