MM - agreed - the narrative doesn't make sense. I've just checked my modest library and I can find no reference to any Spitfires being deployed in the ABDA area before 1945. As mentioned above, these Spitfires are more likely to have been surplus during the British withdrawal in late '46/early '47. Mountbatten had moved on by then (the BMA was disestablished in 1946); in any case it's unlikely that he would have had any interest in the minutiae of aircraft that may not have been 'on charge'.
Are then any websites related to these finds?