An oddity of the Commonwealth War Graves Commission database is that entries for alias names all show up as linked to the UK. I asked CWGC about this and here’s the response:
All ‘Regiments’ in our database are linked to a particular force as all our ‘Nationality’ statistics are generated from this information. Casualties that served under an Alias are nominally entered under the regiment title ‘Alias’ which just happens to show as United Kingdom forces. However, alias casualties do not get counted statistically (the system only counts their true name entry), but the system still has to have a Nationality force linked to it, which in this case happens to be the United Kingdom. Unfortunately, the system does not let us link ‘regiments’ to multiple nationality forces.