Found while translating, so just quickly noting it here: https://koha-community.org/manual/22.11/en/html/i18npreferences.html The page mentions the wiki page and some old command to install additional languages. It would be better to always link to the wiki page. Package commands should be preferred for package installations and the listed command should not be used there. The description of the date formats omits the DD.MM.YYYY format.
Updated the full chapter in the manual.