Question:
Why standard Veeva Align fields, such as the country__aln field on the Territory object, cannot be made mandatory?
Answer:
That is the current behavior for any namespaced (__aln) fields in Align Vaults. If it is required, the solution is to raise a ticket with Veeva Support and the Align team can set it as a mandatory field manually.
Related Documentation:
Align Help Documentation: Align Standard Fields