I put a lot of work into figuring this out before I realized that I could do better with just one metro and a bunch of [mod]'s. Maybe you'll find it good for a laugh.
It has one metronome each for quarter/eighth/sixteenth/thirtysecond notes, and I thought 'hmm I should have it adjust for any differences that accumulate between these.'
I don't even know how well it works because as long as I sat here no differences between the metronomes actually cropped up.