The only times I've been able to find Dice Rooms with a 1 or 6 face ( that randomly reroll your equipped items) it has been while doing Challenge runs, that don't count in terms of unlocks or achievement. So what I'd like to know is: if my equipment gets rerolled to items I still have to find through normal means, does it counts as found for achievements such as Platinum God? Will it appear on the Items Sheet?
I've asked the same question on the SteamCommunity Forum, and this is the outcome:
Nope, they don't sadly.
I know because I've tried it, was getting nothing but Breakfast which meant I had exhausted the entire pool. But none of the items that I needed to find were in the collection page.
There are different opinions, so it's a bit confusing, another guy posted this answer:
I haven't unlocked these yet and somehow they're there.
Meaning that he hasn't unlocked The Lost items (The Soul, The Body and The Mind) but they are shown in his collection page. So it appears to be true.