microG can be translated using Weblate. The microG project is hosted at https://hosted.weblate.org/projects/microg/.
At the moment, microG-UI-tools, an internal component, is not available for translation using Weblate. You may want to open a PR for this. This component hosts strings for the "Self-Check" menu and a few other things.
Preferably do not open a PR for components that can be translated with Weblate. Otherwise, merge conflicts can happen. If you already made a PR, you can try importing the files manually into Weblate for each component.
If your language is not available for translation from a quick look, you may need to first create an account, set your language in your settings, check the project again, and then you should be able to add it.