PSA: If you want to write complex metric modulations, check out this awesome font Florian Kretlow made!

Link to the GitHub page for the font: https://github.com/fkretlow/metrico

It works exactly as described. Before downloading and adding the font to my OS' library, I wasted 20 minutes following someone else's guide only to find out that MS4 doesn't have the Image Capture tool the guide was relying on.

Then, I downloaded the font above and literally all I had to do was open the .otf file to add the font to my OS library, quickly read the instructions for the font's inputs (like 10 seconds reading) and boom, I'm putting in the sixteenth note quintuplet to eighth note metric modulation I wanted.