Adding new translations or updating existing translations to core modules is very easy in AsgardCms. All translations are centralised in the Translation module.
All you need to do is fork that module, and add and/or update existing translations.
The translations are located in the Resources/lang folder, each module has its own subfolder, with under that the different locales.
If you want to add a new language, duplicate the en folder of each module and renaming it to your desired locale. The English translations will usually the more complete ones, that's why it's best to use those as a starting point.