Thank you both.
I think I now know how our projects will style these sorts of things.
I’ve also realized that my true question wasn’t regarding these specific issues. Rather it was: “If USFM is a standard, how do I determine which is the correct marker to use in a given circumstance.”
CrazyRocky’s mention of NIV was helpful in answering this, because it lead me to downloading 10 or 15 different major resources and comparing them. What I found is that there is a shockingly large amount of variance in which markers are used–sometimes within the same project!
My conclusion from that, along with reading the USFM documentation, is that USFM is only a standard in that it limits the number of markers which ought to be used. And in many cases it gives general suggestions for how those markers ought to be used. But it’s not a standard in the way I was originally thinking, as it doesn’t really list exact circumstances when a marker should (and shouldn’t) be used. It seems like it just throws out a group of markers and, with some limitations, says “use these as you see fit”.