It seems to be "gibberish" Japanese that resembles some actual Japanese/Chinese characters, just like how the pocket camp campsite sign is in "gibberish" English
pretty sure it's all fake "text" in any form
What I really wonder about the stone tablet and what the two variants are supposed to say.
If the wood plank sign translations in the link @Hirisa shared are right, then I love the fact that they included Nintendo on one of the signs. "Storm" seems kind of random, though, I wonder if that's right.