The strings for this extension can be translated on Transifex.
Feel free to file issues and describe your problem. I'll likely try to solve it when I find time for it. Or maybe someone else will step up and fix it :)
In theory all you should have to do is run npm ci (after installing npm and node)
and you should be able to launch a Firefox instance with the extension in debugging
mode with live reloading with npm start.
There are some linters and tests. npm test runs all linters and tests.
All code should be licensed under the MPL-2.0. By submitting a pull request you agree that your code is licensed that way.