you didn't say what OS you are running ...
The first thing is imho downgrade, but thats probably not what you want.
Another way I was thinking about, but didn't try yet.
As you probably know, Airsonic is an fork of an older subsonic version.
I'm running Subsonic at Windows10Pro and Airsonic in a virual machine with ubuntu.
Here it is shown how to change the log level for Airsonic and I think it should work at subsonic too, but as mentioned before, I didn't try !!!!
I don't think that Sindre has changed so much in the newer versions.
https://airsonic.github.io/docs/logging/#main-log-fileEven if you are running Subsonic at Windows, there is still the WAR File found at Program Files (x86)\Subsonic
Note: renaming the WAR File to zip you can have a look inside

of course with a copy
