Hey there Roma,
Something that I’ve done in place of using projected decals or mesh decals is building a material that lerps in separate material attributes based on distance field masks. I did this to mask in a dirt texture on a grassy material for a trail carving mechanic, here’s a link to a video tutorial that I made that demonstrates the basic principles, maybe this can work to mask in some blood with a blood spatter normal and different roughness values for your game.
Good luck!