- Can anyone point me to data sources where to best look up country adjectives such as "Mozambican"?
Are you aware of P1549 (demonym) in Wikidata?
https://www.wikidata.org/wiki/Q1029#P1549 has the adjectives you are looking for, at least for some languages. It might not be ideal, but it exists. Encoding further grammatical details (word order, any other words needed) would need to be language specific, but I think you can see how a language-based template pointing to Q1029, P1549, and the Q item for the occupation would accomplish this.