Dan, I don’t want to undermine your efforts… but I just couldn’t resist.
Here’s another solution that may prove a little more versatile than pre-built text objects. Inspired from your threads here I have devoted a bit of time to building a special font for all sorts of metric indications. I proudly introduce Figurato’s little brother, Metrico.
With Metrico you can type strings like in the following examples to create metronome marks, tempo equations and swing indications.
For now this is rather a proof of concept. Basic figures work, most more exotic tuplet combinations are not implemented yet.