Hi @andreas_TR ,
Customer Name, Address, Tax code are additional fields bound to Name Column, they only appear when Name Column is saved, even if in SharePoint. So I suggest you create some custom cards to show these additional fields.
The workaround:
1. Add a custom card in the form
2. Add two labels in custom card
3. set Label1 Text property: Name: Customer Name
4. Set Label2 Text property:
LookUp('List 2',ID=DataCardValue1.Selected.Id).'Customer Name' // DataCardValue1 is the control Name of Name combo box.

Sik