Making a new translation is really quite simple. Go into your Vanilla’s languages folder and copy / paste the English folder renamed to your language’s name.

Then go into the file and change the English definitions to your language’s definitions. You should also be aware that ...

$Context->Dictionary['OldPostDateFormatCode']

... needs to be changed if you’re making a translation, because the default value outputs things like “Jan 30st 2006” (with that English suffix). For other translations you should probably change it to ‘j M Y’, which renders dates like “1 Jan 2006”.

When you are finished, please take the time to upload your translation to the Add-on Repository. Be sure to follow the add-on guidelines.