The quality and variety of sprites will probably matter more than the number of CG in this sort of game. Reserve full CG for climactic points that you want to highlight.
But I suspect your question is actually about the game's presentation on your store page. CG make for good promotional images. Your Steam page is definitely suffering from a shortage of high-quality screenshots--you even included a fairly non-descript title screen! Text screenshots can be ok, but the re-use of the same background in all such images gives a cheap/bland feel and evokes a scope that is suffocatingly claustrophobic (are we really going to be talking to the demon on a single static background the whole game???). Right now the most evocative screenshot is probably the one of the puzzle gameplay.
You need variety and movement in the artwork (sprites, background, CG), in the game also but especially in the screenshots. Even if the game takes place entirely within one room, you'll need multiple backgrounds and perhaps versions of those backgrounds. If your focus is on horror, simple filters over the backgrounds (blur, change in color, etc.) at appropriate moments could add a lot to the atmosphere (really key in the horror genre) without running up costs. And if push comes to shove, generative AI is always an option for increasing variety at low cost--it seems to be pretty decent at backgrounds.
In short, by making good use of sprites and backgrounds, you'll actually reduce your dependence on expensive CG to create movement and immersion.
I suppose I should give a brief nod to what I like too. The character artwork is appealing and the single background you've shown is adequate for the task. The quality is there, you just need sufficient quantity. The screenshots show multiple high-quality sprite poses, which leaves a favorable impression, though showcasing changes in facial expression would further increase appeal.