"hl_02_wallkanban06_" and the other 05 are obviously placeholder textures.
Gotta love these, bottom left seem to be fictitious music bands posters, my favorites there.
They actually have some of these fictitious ads representing things that are actually seen in the game as objects or living things that you can interact with to some extent.
I have no idea if they are references to pop culture or Japanese culture or maybe its just the artist that made his own little universe.
Either way cool intricate stuff you don’t necessarily see in every game where props are at times created and treated as soulless space fillers, these do seem to carry some meaning or at least the fact that they are represented through several forms makes it more believable.