In Trados Studio I can upgrade a multilingual TMX and it will beautifully create all the SDLTMs possible based on the languages in the TMX.
Using the API, with PowerShell, I can beautifully create a Multilingual Translation Memory based on the languages in the TMX and then import it into a Cloud Translation Memory.
But if I use the UI in Trados Cloud I can choose my Multilingual TMX, but then I have to repeat the import with the same file for every language in it. I think it would be a useful improvement if it was possible for the import to handle this automatically and avoid the repetitive steps currently required.