This is typical Apple. Iphone 6 with iOS 12 is nowadays still supported by Apple (only iPhone 5* does not have support) but you do not have any way how to test it! Simulators support only newer devices! Thank you great Apple!

Terrible problem. We can add as many APP ids as we want but grouping supports just 5. We successfully configured Facebook and also Google sign-in for in about 10 app variants but it is not possible for Apple. Apple should increase this useless low limit.

No. Information in Membership details are some another. If I want to edit bank account holder apple offers checkbox "Use the same as Legal Entity" and when I check it, it fill-in address with typos errors. In membership details address is correct. So question is that where else have Apple stored "Legal Entity" information to edit it?