>>282912685
I couldn't find any exact matches for the other talismans, but the one Otoya uses here has a direct real-world equivalent. It's part of a set of 72 protective talismans known as 太上神仙鎮宅霊符, or "Talismans of the Most High Gods and Immortals for Home Protection". I think the text says that this particular one deals with protecting against malicious spirits of some sort. It appears several times across the series: here's a picture I made a while ago with a later appearance.
The picture on the right is from a 1915 book called 信仰叢書, which I originally found via the Wikipedia page for Ofuda. There are a lot of modern books which compile talismans like this, too, so I imagine Rumiko has one or two that she can pull designs from as needed.
Like onmyodo itself, most talismans like this derive from ancient Chinese mysticism, and their composition usually follows certain rules. Typically the idea is to use specific symbols and characters to charge the talisman with yin or yang energy and define what you want it to do. I think the dots on the top are meant to represent constellations, and there's some sort of spiritually-charged phrase on the bottom, but I can't tell you anything beyond that.