Rather than going to all the way to 223, I think I'll start with Lillie. I doubt devs intended for people to find everything before choosing her, and with some luck that room might be the same in this run anyway.
Here's an imgur album ID for related material: uikNEpH
And another with some newer stuff: aidMTpY
There IS actually more to the game, my current bucket list:
-Floor B223 (again)
-Getting the last shortcut hint.
More investigation towards the last area of the game.
The 5 picross I picked up are now solved. Considering that every shortcut had one, I'm missing at least 1 puzzle at least.
I've solved half the alphabet, sadly I don't have the mural messages from mural 6 and 7 to get more letters from, if anyone have them I'd e thankful if you could link them. The weird dots with the shortcut hint chart just says "MON WAS HERE" (and it's also how I got the pattern for the letter H)
Also, probably useless, but I noticed how none of the shortcut entrance/exits were an even number, then I noticed none of them were 5s either, which I found suspicious until it clicked... they are all prime numbers, so shortcut 5 is likely a prime number as well.
Additionally, I originally thought that statues were placed as some sort of post-death reminder for void lords, but this made no sense due to tan having a statue. Then you notice that only the traitorous lords are lacking one.