When producing TreeTrek, I went with rudimentary diffs that account for colourblind developers:
https://repo.autonoma.ca/repo/treetrek/commit/3fe9360599ae23...
The diffs rendering library looks amazing: https://diffs.com/
Presumably the red-green issue is a simple CSS update?
Yup! You can pick from a bunch of different themes and use css variables to override the core colors as well!