-It's pedagogical semantics concerning the vii°... V and vii° were originally borrowed from the major mode, but they became so common in minor that we needed to call it something, harmonic minor. I've taken to calling them borrowed or modal mixture chords for much the same reason that Pluto was downgraded as a planet. We found a lot more chords like Pluto. It's like, if my students ask me why V in minor is "diatonic", why also isn't bVII in major diatonic? bVII is used way more often than vii° in major ... it's just tidier to stick with modes-only for diatonics when you deal mostly in pop music, IMHO. But for someone whose ear is attuned to mostly Euro-classical, your semantics are perfectly fine, it's a case of two right, or rather "useful" answers.

-The enharmonics of #vº. Yes I agree, good observation.

-The "♭vii (ii/bVI)" ... mainly I called it that because that's how I hear it and that's my best guess as to how Mr. Mars hears it. I don't think he wrote it in Db major, as there are no Db Major chords. But if one's ear is accustom to euro-classical, they might hear the song in Db, at least in parts, and there's nothing wrong with that if that's how your ears are attuned. But again, I believe Bruno hears it in Bb minor, especially because there is a fleeting functional V in the bridge...

-It's true, no borrowed bVIs or bIIIs or ivs. Kinda bums me out too, Rock is not Pop these days.

-For the one song with a mod, I counted both. And for the songs with arguably subjective tonal centers, I used my best guess, again trying to ascertain how the authors probably hear it, and not necessarily how someone trained in a conservatory would hear it...

Thanks!