This is an anthology: I half expected it to be something meta in which the author assumes different voices, but it appears to be an actual anthology from different authors :)
If not, that's quite a writing feat because the stories all have markedly different styles. If it is an anthology, it is still great work to a/ have gathered all this great material and b/ have come up with the great framing device that is Castle Balderstone. I haven't played the first game yet, but I surely will!
Have a go at it if you like being spooked. You will be many times!