English language between en and en-AU and en-GB

I am experiencing the same issue.
Seems that whenever there is an specific language defined (en-AU), it does not use the general one (en) to resolve any other specific language (en-X).

Moreover, if you define en-AU and en-GB, then en-IN will rely on en-GB BUT en-NZ will rely on en-AU... seems to be alphabetically ordered and rely on the next one... or??

Apple documentation says: https://developer.apple.com/library/archive/qa/qa1828/_index.html
"The dialect support in iOS may slightly change the above behavior. If your user's preferred language is a regional variant that is not supported by your app, iOS will try to fall back to a more generic language before giving up. For example, if your user's preferred language is British English and your app bundle doesn't contain an en-GB.lproj or en_GB.lproj folder, iOS then searches your bundle for an en.lproj folder and chooses English for your app if the folder exists."

This is not happening if you have another regional language defined.

Question is: Why en-GB does not rely on general en ?? is this an issue?

In order to fix this, there is an specific en-001, we added that to the project and fill the values with the default ones. So it only resolves en-AU with australian english, any other specific english will rely on en-001