Would it be possible to have the message only send to server operators?
It's kinda pointless to have it be sent to all the users in the server who don't necessarily have control over the situation

That may work for you if you have stable versioning on the modpack, but on a rolling setting, toggling a config file before every tiny external update (note: we don't have a staging environment yet), can get quite annoying

Also I should add: pretty sure that this mod runs on both sides, so it shouldnt be an issue to add server exclusive behavior

the logged message is client-side, iirc. would probably be best to just fix the broken tag with a datapack OR ship your modpack with the config to disable LMFT warnings

I have fixed the tag and the config is in place, but I would like to know if/when the issue shows up again without bothering people that can't do anything about it

just remove the config that suppresses the warning for yourself. that's what i did for my modpack and it worked fine. during development of the pack i had the mod installed, and by the time i shipped the pack i had fixed all of the errors, so i didn't even need to ship it to end users