Hubzilla UI language doesn't change to safari's default browser user language

@Hubzilla Support Forum+ The #ui (user interface) of a #hubzilla hub automatically switches to the default #language of the #browsers google chrome and firefox, but not of the browser #safari. Why is that?

Tested with (language: brasilian) and (language: english) on safari 11.0.1 with browser's default language german
What *exactly* is the language setting? Hubzilla supports 'de'; (German) but sometimes browsers offer very specific options, such as the specific German dialect of German (de-DE); and Hubzilla doesn't know about this specific language variant so reverts to the default. One can often correct this by adding 'de' after or in addition to 'de-DE' in the browser config.
It seems that one can specify "German (de)" instead of "Germany-German (de-DE)" in Google Chrome and in Mozilla Firefox. It's the default specification for me. I tried to do it also in Safari and in Brave by opening the preferences in the menu. Brave offers only "Germany-German (de-DE)", Safari doesn't show any language options... So at the moment I will stick to Chrome and Firefox.