Hi, karito
Thanks for contacting us.
Firstly, please follow this documentation learn more about how to translate this theme:
http://docs.yolotheme.com/begreen/#translation_rtl
In addition, if you want to have language file on the child theme. You need to create the link of Child Theme folder that looks like parent theme.
Then go to Settings > General > Site Language > change your language.
- See your image, you haven't changed the name of the .mo file as our guide yet . You can follow the language code link to change the name exactly:
https://make.wordpress.org/polyglots/teams/
Please read our documentation carefully, then check it again.
Best Regards,
YoloTheme