Could the list you have there be for LIFT export only ? For a while now we are doing exports to DAB via the “configured dictionary XHTML” and I have not seen a (custom) field that cannot be exported.
You are right that media files (audio) that is imported into flex and can be played in flex does not play in the DAB app, whilst audio recorded with Flex can be played in an app created by DAB.
The quality status in Flex is defined per sense and not per entry. So indeed, as you suggested, it required a new custom field to be able to express the quality of an entry.