I found this information some days ago but accidentally sent it to another person - oh dear I hope she was not too confused. Anyway I hope it is still of use to you. If you look under
www.lcmsouthernafrica.org/St_Annes_Hospital_History.pdf you will find that Mother Berchmans was just on a visit to Salisbury (Harare) when she died suddenly and was the first Sister to be buried in the Little Company of Mary section of the Pioneer Cemetery in Salisbury (Harare). However I have failed to find any entry of a death in the Death Index under either Berchmans or Cotter, which is quite odd. eGGSA has a cemetery photo project which includes graves of South Africans outside South Africa. There are quite a lot for Rhodesia (Zimbabwe) and whoever has taken them obviously just photos graves without any reference to whether they are South African or not. I have found a gravestone for someone I know who was never anything other than Rhodesian (Zimbabwean) and another for a husband and wife who were refugees from Hitler's Germany and may have visited South Africa but were most definitely never South Africans. However, for some reason , there are no pictures at all for any cemetery in Salisbury (Harare). Several for Bulawayo and some quite obscure places like Gatooma (Kadoma) and Sinoia (Chinohyi). If I come across any more information I will let you know.