Do you have a source selling sub-species-specific C. amboinensis? Here in the U.S, locale-specific animals are offered occasionally (i.e., Seram Island is one I saw recently), that seem to vary in coloration, body and head shape, but nothing drastic. I would doubt that the whole complex of C. amboinensis is even properly identified. There are likely more sub-species than have been identified. Four are recognized currently, I think, but the outlook of finding properly identified sub-species to me seems like a longshot.
You may want to factor in how aquatic you want to keep them as well. Some ssp. may be more aquatic/terrestrial then others.
You have new picture to share with us??View attachment 118680
Can the plastron tell them apart ?
They do varies .
Will make a more recent picture in a couple of days !
Sorry for the late answer no sorry I'm not an expert of amboinensis so I can't tell you the differences..
But I'm still thinking that amboinensis have minimum 10 different subspecies not only three that's not enough for an turtle kind which live in so many isolated Indonesia islands!