I'm not sure if I'm right, but I spent a lot more time than I should have poring over the codes and this is what I think.
The codes are to be read backwards, as in, bottom right to left, then top right to left. You'll notice there's a series of four recurring letters on most of the purple blocks on the first floor... they mean 'king'. I'm not sure how to post pictures of the symbols, so here's an alphabet with my description of what the symbols look like.
A = ≠ (but the diagonal goes the other way)
B = circle with four vertical-ish lines under it (kinda like an Egyptian sun)
C = three squiggly horizontal lines ( ~ like that, one on top of the other)
D = Δ
E = arch or semicircle with a dot in it, like an eye
F = the game freak symbol.
G = two squares, one within the other, missing their tops.
H = a diamond.
I = sort of like a capital i with a horizontal line through the middle
J = not sure.
K = like a fork or trident pointing southwest.
L = two horizontal lines, one over the other, with circles on their right ends.
M = a spiral.
N = kind of like an X
O = four small circles forming a diagonal chain.
P = an arrow pointing up with two curved lines underneath it.
Q = not sure.
R = like a sun.
S = looks like the letter V.
T = a curved, horizontal line with a circle on either end.
U = looks a little like a crown. three points facing upwards.
V = a full circle within another full circle. Don't confuse it with E's symbol.
W = four vertical lines, rather like claw marks.
X, Y, & Z = not sure about these either.
Hope that helps. Again, I'm not entirely sure I'm right, but i'm still very confident. If someone's already figured this out, I'm sorry for reitterating. I figured this out almost on my own though. Sorry I couldn't find J, Q, X, Y, or Z. Good luck!