@Steve Robinson
Yeah but welfare wise surely as a male Putra Mas will weather better than Permai, her being without Tricia's companionship for over two years now. Do realise that with Putra Mas some degree of contact with Permai (and until their deaths Tricia & Teduh) even if just visual contact would have benefited him all the years since he moved from living with them to his own exhibit.
Really do think on an overall welfare scale that for Permai and Burma to meet one another at Monarto asap and fingers crossed form a bond seems to be likely the best trajectory for the both of them based on the importance of female eles' social grouping natures, and would be less of a significant issue for Putra Mas to live without the contact at all, not the best outcome of course, but comparitevly speaking. Lets hope his crate training does work although the compounded issues 24 years later like you said could stop that, hopefully not.