Wait, you maybe right.
I remember reading something about the fact that they are multiple person working with him, but i think, from memories, it's from stuff like his FPS developed on Unreal Engine 5, ASMR stuff or the dakimakura.
If you really wanna know, check out his ci-en blog. I dunno if the rule of the forum allow me to post a link here so i don't wanna risk it, but you can find the link in the Fallen priestess game description (on F95) or in the DLsite description as always with ci-en blog.
All in all, i will bet it's bbq lover who do the art, but now i'm not 100% sure ^^