That would cause confusion with Speed of Light and Lightspeed being two distinct speeds. Also, why would we make an entire speed role dedicated for an exception of verses which don't act like the other? For your first example, we can just place those people at SOL and Infinite if they have the feats for it. This is heavily reductive and adds nothing.
I believe light is set to light in a vacuum, but I could be wrong. Sound I believe is in air.
Breakdown is easy:
1. By default, lightspeed is the speed it moves in a vacuum, free of gravity or manipulation. That's not changing.
2. You misunderstand Hop's point entirely, no idea where that came from, didn't say SoL and Lightspeed needed to
both be listed and distinct. What Hop meant was: How is this a concern, light itself acting different verse-to-verse? These verses typically display and explain how that is so, its on the verse and those of us who write pages for them to elaborate. Hypothetically, if a verse has MFTL+ as its base for light's speed, then we can continue to call it MFTL+ or what have you. We are always referring to the real world with our wiki terms, or at least commonly understood fictional concepts, like say, matter/atom/physics manipulation. Light rarely is changed for such reasons in fiction/verses.
3. "Speed of Light" is lengthy (and sometimes characters in this realm of speed/power/etc are crazy large as it is), so you can just rename to Lightspeed on the speed page if that makes sense. Pages, of course, need not be updated to reflect that change. Waste of time and edits for what literally states the exact same thing. If "renaming" it makes sense, then that's an easy but not hefty change for us. Wordy pages for the sake of sound smart are more frustrating for new users than having to read definitions of Wiki terminology in the first place. They typically are smart enough to understand there would be things here over their head (and even us staff at times, too).
------------------
Side note on the second topic:
Sound is correct, as it has variation based upon what sound travels via. For example, metal transfers sound much faster, fast enough to blitz several common characters. But that's a rarity and sound often is just audible vibration. Unless we're talking SCP levels of hax, where the sound is used to create some horrific metaphysical effect to bypass durability, it's speed really wouldn't even effect specific events in VS threads.