Gitea’s localization happens through our Crowdin project.
For changes to an English translation, a pull request can be made that changes the appropriate key in the english locale.
For changes to a non-English translation, refer to the Crowdin project above.
Any language listed in the above Crowdin project will be supported as long as 25% or more has been translated.
After a translation has been accepted, it will be reflected in the main repository after the next Crowdin sync, which is generally after any PR is merged.
At the time of writing, this means that a changed translation may not appear until the following Gitea release.
If you use a bleeding edge build, it should appear as soon as you update after the change is synced.