If a card you banish to play has a check that can allow you to do something other than banish it, put it in a recovery pile and attempt that check at the end of the turn. You should also put it in a recovery pile if you have a power on your character card or on a displayed card that can allow you to do something other than banish that card.
The issue is, Quinn doesn't work very well with some conversion stuff.
Here's Quinn's power:
"You are proficient with Alchemical. On your check to recharge an Alchemical item whose level is lower than #, you automatically succeed."
Potion of Healing, however, doesn't have a check to recharge, so it isn't subject to the conversion alteration. This means that Quinn can't recover it, since his power doesn't interact with PoH either.
In fact, the new wording on the Alchemists don't interact with Potion of Healing either.
Am I missing something or is Potion of Healing currently broken in Core? I feel like I'm missing something big here.
I'm playing Quinn in two different campaigns: an OP campaign and a regular (non-OP) Crimson Throne campaign. The OP campaign is relatively new; we did Fangwood Thieves and We Be Heroes, and now we're starting Season 6. The non-OP CotCT campaign is almost finished (starting AD6).
In the OP campaign (using UE + Rogue decks), I wasn't planning on ever taking his alchemical power feats. In agreement with your statements above, they only work on Core/CT cards acquired in-game or cards substituted from the Core/CT sets (e.g., Noxious Bomb). But Quinn doesn't have the Craft skill or a high Dex, so the combat-focused alchemical items aren't very useful.
Quinn's alchemical powers are quite useful in the regular Crimson Throne campaign. He doesn't have many alchemical cards in my build, but the ones he has work well (Elixir of Healing, Elixir of Focus).
My understanding matches yours. With the exception of the very few alchemical cards that you pick up mid-scenario, you somehow have as Loot, or you can replace with same-named Core/Curse cards; Quinn has absolutely no capacity to use Alchemical items in PACS. I would highly advise any player using him to avoid his Alchemical-matters powers entirely, and simply build him to emphasize his Knowledge-Finesse-combat and anti-barrier powers.
Speaking from a theoretical perspective (I've got PACS Tier 6 decklists/builds for most Core/Curse characters), Quinn isn't great in PACS right now, and his inability to use Class/Character/Ultimate Deck alchemical items does greatly inhibit his possibilities. There's certainly still some interesting things you can do with him (if you want, you can just replace his item slots with spells post-role, not that he'd be able to recharge any of them), and thankfully he is able to pick and choose literally any class/character deck to be used with alongside Ultimate Equipment, which is a seriously useful feature... but I personally have no interest in playing Quinn in PACS until some new Class Decks hit for him to use Alchemical Items from.
For what it's worth, I think Jenceslav's solution is elegant and practical. Especially since it shouldn't break almost anything because so few characters have Alchemical proficiency anyway, let alone could pass high Craft checks.
By the way, this impacts my choice of Quinn in my upcoming game. While he can do other things, I like the Alchemical aspect of his stuff and not being able to use that in PACS is a big detriment.
(In fact, it impacts my choice of any character who uses Alchemical items, with the possible exception of Drunken Master Sajan who bypasses this by having a check to recharge.)
By the way, this impacts my choice of Quinn in my upcoming game. While he can do other things, I like the Alchemical aspect of his stuff and not being able to use that in PACS is a big detriment.
In OP, Quinn is also extremely limited in his weapon options due to his need for stealth/acro skills and his lack of weapon proficiency. I'm curious how that will work out long-term. My plan is to use dice-adding poison items to enhance his combat, but we'll see.
In regular play, Quinn has access to solid weapons in Crimson Throne (if he can find them) - and one fantastic loot weapon.