There are only 2 casualties in Lubumbashi cemetery:
Major Boyd Alexander Cunninghame, Argyll & Sutherland Highlanders. Died 16th March 1917.
Captain Gordon Williams, Welsh Regiment, died 15 November 1918.
Maybe some sort of clandestine missions?
ADDED:
From 1910 the city was called Élisabethville, and it was the centre of the mining industry, and was on the border with Zambia (Northern Rhodesia).
Major Cunninghame was on leave when he died.
No notes on CWGC for Captain Williams.