It is very important to understand how Brasato decides which bundle and language should be used to translate a key. The following graphic will help you understand the translation fallback chain to find the right translation. Let's assume the system tries to translate the key "hello.world" from the bundle "org.olat.hello.world". The user has the language "de_CH" enabled in his user session:

First, the language overlay is considered. If nothing is found there, then the system checks for the translation in the users locale. The locale is first checked against language, country and variant, then against language and country and finally only against the language. If still no translation has been found, the system tries it with the configured default locale. Note that the default locale is a configuration made by the system administrator. Since the chosen default locale might not be translated completely, the system uses the hard coded fallback locale as the ultimate fallback mechanism if everything else fails