Have you searched those terms on Etsy? When I do, I can see that they pull up different search results. Some of those terms seem stronger than others. "Frankenstein artwork" for example, only pulls up 30 items, while "Frankenstein art" pulls up 1,300+.
I personally think it's okay to have a couple of different Frankenstein searches to match what your customers are searching for, but you should probably choose the ones that are the strongest and not every variation that you can think of.
You might think about removing some of the very general words like "print" and adding more specific phrases ones that would help your ideal shopper find you like "monster art" or "horror movie." (I'm not an expert in that area, so you'd have to figure out what those other words might be.)
You might also tweak your titles. You come up at the top of "Frankenstein artwork" searches because you have those words in your item title.
Hmm . . . I guess I had a lot of say about this. Hope it helped!
