The relief/emergency/temporary hospitals were (building on this thread https://gwulo.com/node/37475):
University of Hong Kong
St Paul's (attached to main hospital)
Happy Valley Racecourse
St Stephen's College (Stanley)
St Stephen's Girls School (?)
Stanley Prison - moved during the fighting to become the basis for what was to be Tweed Bay Hospital in Stanley Camp?
Hong Kong Hotel
La Salle College (Kowloon)
Peninsula Hotel (Kowloon) - never opened
Central British School (Kowloon) (?)
I've put question marks by three locations because I've only seen one source for each whole the others are well attested.
This source seems to suggest that the Central British School (now King George V) was turned into a military hospital in 1940. If so it probably continued in that capacity through the hostilities:
https://www.kgv.edu.hk/history/