Typst doesn’t have line spacing, hence the Proposal: change `leading` option to `line-height` · Issue #4224 · typst/typst · GitHub. There is only between-paragraph spacing, which is still using leading.
#set par(leading: 0.75em, spacing: 0.75em)
I’m not a font expert, but if you can make everything look as you want right now, then you can just publish the template and create a new version if any problem arise in the future.