install and update the localization files in osu!lazer with rūrusetto
Localisation files can be obtained at rulesets status page and then clicking on the Download localisation file on the desired ruleset.
The changelog and download link will automatically update when a ruleset is updated.
In osu!lazer’s setting panel, there is a button to Open osu! folder within the “General” section. On windows you could navigate to the data folder directly via Windows Explorer, by default this location is %AppData%/osu!/rulesets. On MacOS default this location is in application itself.
Extract the zip that you just downloaded, the folder(s) for languages are set by their ISO codes. To install your desire language, get in the folder of your language, grab .dll file inside the folder and paste it inside the language folder.
Other rulesets also could share the same folder.
After completing the above steps, you may need to restart osu!lazer if it is already open. Once restarted, you should see the localized text in the rulesets setting part. You can change the osu!lazer's language in the General > Language section of osu!lazer's settings.
To update localization files, just do the same step and overwrite the old localization files.