You need to realize that the laws don't spell out every situation exactly. Laws being open to interpretation is one of the few things that make Tribunal even moderately interesting to play.
But using a harmful power IS absolutely a crime, even when there's no victim. It's specifically spelled out separately from the "don't kill people" law. Enforcing the law as-written is a perfectly viable option for a Tribunal. So yeah, your bard singing battaglia could get a warrant for it, even if no one's in the room.
The third law makes it illegal to aid known criminals. It doesn't spell out exactly what that means (it gives examples, but ends in "etc" which means.. anything else you think of). If there is a wanted person online, and you're doing anything at all to hinder a Magistrate (including making them visible), that could be interpreted as helping them and breaking the law.
And as far as lullaby - There's nothing in the law that says someone has to yell for it to be a crime. Magistrates are expected to investigate, not just sit around idle and listen for yells.