It's sending sound parameter information (e.g. filter cutoff at 12khz, resonance at 1.6, Q of 0.89) along with note information (e.g. start playing note A4 with velocity 80). You could absolutely use a MIDI CC channel to convey this information. The OP-32 chooses a different route and encodes this into an audio signal so that it can transmit it over the air using the speaker/mic instead of a wireless stack.
what you mean? synthesisers are software... I think the context is clear here and we're talking about software made for music, so the usage of patch is accurate. If author wanted to use "patch" to mean patching a file they would likely be specific or context could be inferred.
"A patch is data for modifying an existing software resource such as a program or a file"
Which is what patching synths/drum machines (and files) does.
The specific values of all of the settings on a synthesizer (including the inputs and outputs of any cables in a modular synth) have been referred to as a "patch" for a very long time. That's why the cables are known as "patch cables".
If you, for example, download sysex files for a DX7, they will often be referred to as "patches".
https://youtu.be/TLzAyouLQxw?si=mm6goX-cMyEZkwOI&t=102