Man, sorry for the late reply, was on a trip and away from my computer for a bit. Let's see.
Ah okay, thanks. I'll keep plugging away at them whenever I do a run. Feels like I keep finding the same 4 hints so far, but admittedly I hadn't been paying attention to them before learning they had a meaning so the "pool" I've been exposed to is still small.
Right after you hinted at them, I thought I could be sneaky and save my game before grabbing a cursed soul, then quitting out after grabbing one to try "rerolling" them, but it looks like that was planned for in advance because whether or not souls have alternate messages seems based on the number you find, as well as those messages being predetermined at the run's start.
They are predetermined, yeah. It's guranteed to show you all 8 after you first get the achievement, but then it's random after that. FWIW, one is completely unnecessary, and you can get the sense of what you need to do after a few.
Edit: Stuff like this is why I don't mind redoing her quest.

Mission accomplished
- I kept forgetting to ask if this is a bug or not, but is it intentional that Reikon's bubbling poison still damages you if you're using Float? The spell seems to let you ignore the damage of other floor-emanating traps, but not that.
That one's intentional. In Reikon, since you're guranteed to have float there, Aevin wanted some way of enforcing floor damage still. The bubbling was meant to indicated that it still splashes upwards/there's vapor in the air.
- Jandra's boss room seems to switch up on you when she changes phases to drop her big ultima attack, regrowing the grass and placing the spikes in different positions. I don't know if this is intentional or not, though.
Yup. it's intended. Back in original pre-update Yuurei, before power creep took over, it was a big deal even.
- Also, I noticed that the way Dracus and Holm regenerate magic over time isn't consistent. Holm's is interrupted even if you're casting free primary attacks but Dracus's will ramp up as normal.
Not fully intentional but I don't think I mind it.
- Hover lets you float over gray razor blades in Challenge Styx and the Factory zones.
Now that one is unintentional.
- While technically not a bug, I think this hidden spot feels a bit unreasonable to access, as you have to be vertically pixel-perfect to find out there's water you can swim through to reach the item inside. Using Hover will auto-align you with the corridor if you happen to have it, but it's weirdly difficult to squeeze in if you don't.

I suppose that's why the ice is there, but I imagine a first-timer in this room wouldn't know there's water to push against in the first place, so the ice would be misinterpreted as a simple floor hazard.
There's another way in two rows south, just above the shutter. This room actually is a mirror of the first room of the area.
- Also, you can hang the game when trying to form a Fragmented run by setting your seed to 0 0. I noticed regular maps don't allow you to do that, but there's no block in place for fragmented ones.
Whoops...
- Putting this one in a spoiler window because it might be a bit nauseating, but when holding down the attack button when you step on these debuff-stacked red thorns, the effect can loop for a considerable amount of time like this.
Is it bad this one's kinda funny, if not epilepsy-friendly?
- If Maria takes the form of a stationary enemy while standing on a recovery tile, you become stuck and have to F6.
Welp, that's a problem...
I'm afraid I got myself another another seed where spells are locked behind each other. While it's still finishable without the missing spells, if I hadn't been playing as Maria, then I think both Flake Shield and Quake would be impossible to obtain because, well:
The seed also placed Shadow Magnet behind a shadow block check in Lac D'amour, although both Conduit and the elemental canister are accessible so that's *technically* within some logic; I don't know if the item placement takes that into account. I have no checks left that don't require one of those three spells without sequence breaking. Fragmented, no labyrinths banned altogether but:
Seed: 1 1, Yuu Rand mode
Hash: EDAB AACA CECA JAAT ACQA C2AAA TBAEG
Yeah... I am strongly suspecting the item placement just outright broke a while back and has been placing them logicless, and we just haven't noticed. Or, well, I should say one of the item placement logic arms. Separate branches deal with progression items in Fragmented on an labyrinth-wide level (no putting fire behind an exit you need fire to get through) and screen-specific checks (no putting shadow magnet behind a dark block), and I think the latter must not be working for some reason. Not looking forward to that...
Probably unrelated but I've never actually done this puzzle legit before. I know there's some kind of elemental orb at the end, but the red cross blocks above and below negate both PK Thunder and Photon. I assume it's a light check because Thunder doesn't break the orb either.
(I've always blinked past the diamond block to cheat it before, but I think Yuu Rand mixed Blink behind what would've been one of the Quake / Flake Shield checks this time)
It's a photon check, yeah.
I'm wondering if something about ZC 2.55(.?) is affecting things like this? Since one game bug was already related to it, it sounds more plausible than the quest somehow never creating these situations by chance until one player pulls a hat trick of them several years later.
I think it's probably more that I broke something with it somewhere along the line, and the items in Yuurand allow for enough creative spell usage that it wasn't noticed until you came and stress-tested it so thoroughly.
Edit: Came back in the morning to finish the seed and it didn't assign Nightwaves anywhere at all either, which I've never seen happen before.
... Man. That worries me. Unless wait. If it's a soul hunt or Ayn Yuurand seed, I think I know what's happening.
- In Lunar Tower C, if you have both a gold and regular key when you try to unlock the gold barrier (doable with Blink), a regular key is consumed instead and the other gold barriers will remain up forever, preventing access to the solar side's boss. Presumably the purple lock has the same problem, but you can blink into the lunar side's boss room anyway so it's not a problem there.
Oh, this is the same issue you had with the colored locks before. Easy fix at least.
- If you reflect or catch Naira's bubbles to use against her, they split into many Wills on impact.
Sword Beam weapons are magical creatures. I don't think I can actually fix this one without reorganizing all enemy weapons in the tile pages, and we're short on tile space and have a bunch of hard-coded tile checks. Man.