My league location is a place that cares about the silver ball, and they have as many or more pins than vids. There's a logbook of pinball issues you can report and they get fixed.
As a photographer who sometimes plays pinball, I might carry a camera tripod hotshoe with a small bubble stick (like in a straight edge) that I can set on the glass near the lockdown bar if I suspect a table is off level.
As for trying to level games myself, probably not, at least where the games are cared for, and if they're not they're probably unplayable for other reasons.