If you want to edit an existing translation (Fixing typos, Updating it to a newer version, etc), you can just use the github file editor to edit the file.
Please DM me on discord (tobspr#5407), so I can add the language template for you. It is not as simple as creating a new file.
PS: I'm super busy, but I'll give my best to do it quickly!
## Updating a language to the latest version
Right now there is no possibility to automatically update a translation to the latest version. It is required to manually check the base translation (`base-en.yaml`) and compare it to the other translations to remove unused keys and add new ones.