I asked the developer about the ability to export lyrics when exporting musicXML, here's his answer:
"The lyrics feature in MusicXml expects for lyrics to be broken down into syllables and each syllable given a time element for when it is sung. I don't have timing data at that granularity so I'm not exporting lyrics. There may be another way to get lyrics that I'm not aware of. I may be able to export a bunch of words at a time (not syllables)--similar to what I do with pdf export."
Exporting identified notes is currently supported via a midi file, not via musicxml. Maybe in future versions...
I totally understand, hence my "should != does".
I've had so much experience of people short-circuiting specifications because "that part doesn't apply to us" or because they think there's something unnecessary in the specification, or because they don't understand it properly, or because they overlook some part.
I'll give an unrelated example that shows the kind of thing I mean. A client complained that a product of ours was consistently "locking up" after about three days, needed a power-cycle to clear it, was rubbish and needed fixing. When we investigated it turned out that their product had no means to receive the "Done" replies from us, so they didn't bother offering us any opportunity to reply. The consequence was that we held on to the replies until we eventually ran out of memory. They agreed to send us the offer to resolve the issue; we also independently implemented an "abandon message" at a high-water mark in case anyone else did similar.
That was a very simple protocol. MusicXML is not simple; there are lots of opportunities for mistakes, misunderstandings, "doesn't apply to me" and the like. Even if one uses a sanitised and proven parser, there's no guarantee that the resulting data will be used correctly.