please make it compatible with language fallback plugin

When i have both plugins installed backend stays german.
but when i need help from an english speaking person in need only the backend english.
Please improve.

https://www.ads-software.com/plugins/language-fallback/

Starting with WordPress 4.3, you can use languages such as “Deutsch (Sie)” (formal German) in your WordPress installation. But if the themes or plugins you are using do not have a translation file for this language, WordPress would use the default language, usually English, instead. With the help of this plugin, you can set a fallback for your chosen language. Every time a translation file is loaded, the plugin will then load the fallback, if a translation for the originally chosen language was not found.

https://www.ads-software.com/plugins/english-wp-admin/