I added descriptions (taken from Wikipedia) for the following countries:
Asir U14
Australia AST
Austria AUS
Canada CAN
Czechoslovakia CZE
Hungary HUN
Netherlands HOL (taken from DH)
Newfoundland NAM
New Zealand NZL
Sinkiang SIK
South Africa SAF
Still missing descriptions:
Crete CRO
Congo Free State U00
Hawaii U04
Korea KOR
Mahdia MAD
Morocco MOR
Orange Free State U19
Portuguese Empire PRK (+ picture)
Qing Empire QUE
Sokoto NIG
Samoa SOM
Darfur SUD
Transvaal TRA
Italian Regency of Carnaro RSI
Free State of Fiume FLA