Alexander Frater, in the book I referenced above, wrote that when he was on the spot and he went looking for detail of the Imperial Airways flying boat service, which passed through Malaya in the 1930s and must have been a real significant event, he consistently found no records or even interest in the past, it seems that historical detail is not a universally shared interest round the world.
There may well be more details of the early Malayan fleet in the various A J Jackson/Putnam books published in the 1960s about the DH Rapide, the Avro Anson, and the Airspeed Consul (this last type we have not discussed yet but Malayan also had them in its early days). I don't have these any longer but others maybe do. Same author as had the photo collection referred to above.