If you can set the text property and see your text, then it's not an issue with the embedded font.
This seems like it may be a bug in
flash.text.ime.IIMEClient on Android (which provides the text input events used by
TextBlockTextEditor). As you said, it works correctly on Windows, and I would bet that Adobe hasn't tested it extensively on Android. Those iOS limitations mean that few in the community would find value in creating a custom text input controls on mobile, so there aren't many people that would would even encounter this bug to be able to report it to Adobe.