Duh! Color me dumb!
I wouldn't be so hard on myself. There's clearly room for interpretation.
...I guess I thought it was an altered tuning of the reeds, but it turns out it's more like a different "section" of notes on the harp. Is that somewhere in the ballpark?
Yes, but more people will understand if you say it's a different "tuning" or maybe even "layout." Tuning refers to how notes are assigned to holes and layout refers to how the reeds are arranged in the holes, if that makes any sense.
In any case, if a 14-hole qualifies as an orchestra tuned instrument, then my Suzuki Sirius 56 (14-hole) qualifies. Since I play that harmonica more than any of my others, I think that makes orchestra tuning my "go to" instrument. I must say I find it a bit confusing to consider adding a couple of holes at the bass end converts my harp to a different tuning! It just feels like a regular harp in C with more notes at the bottom. Whatever, I'm all in for orchestra tuning if that's what I've stumbled upon that I happen to like!!
Yes. Your Sirius 56 counts as an "orchestra tuned" harmonica, not because it has 14 holes, but because of the notes in those extra notes on the bottom. Orchestra tuning really refers to your harmonica having the same compass, or range of notes, as a violin. This allows you to play parts written for a violin. The compass (range of notes) of a "standard" 12 hole chromatic harmonica in C is from middle C to D four octaves higher and skips over the highest C#. The compass of a violin is from G below middle C to about E four octaves higher and obviously doesn't skip the C#. So, a standard 12 hole chromatic cannot play the lowest notes that a violin can. Your Sirius 56 goes from the G below middle C to the D four octaves higher, so you can hit those lowest violin notes and *almost* reach the highest ones.
If you want to get REALLY PICKY about orchestra tuning, you can say that the harmonica shouldn't skip that high C# in favor of the D. The Violin Scale Tombo Band Chromatic (That's the actual name.) is a valveless chromatic in C that starts on a G like your Sirius 56, but doesn't skip the C#. Tombo calls this a "violin scale" harmonica. Some people might refer to this as a "true" orchestra tuning. Some people might roll their eyes at this definition. ;-)
The reason 14 holers qualify is that MOST 14 hole chromatics are orchestra tuned, but this is not a law. It is possible to tune a 14 holer starting on a C, or any other note, and add the two "extra" notes at the top. This could definitely make sense for "keyed" harmonicas in lower keys.
It's also possible to make an "orchestra tuned" 12 hole harmonica by just not having the highest notes, but again you'd be missing out on the highest notes that a violin can cover so...
Personally, I think the best definition of an orchestra tuned harmonica is one that has approximately the same compass as a violin so that it can, in theory, play music written for violin.