I use a different tool, visidata. It's especially nice when used as a psql
pager.
A text editor isn't the right tool for editing tabular data, imo.
As for KaTeX, what I would do is have a preview process running outside of vim that watches for changes in source files and re-renders. That's the Unix way of doing things.
It's how recruiters find me, so unfortunately I can't. I almost never open it, though.