It's a terrible idea! At least as described... I don't know why you're so determined to reduce the number of galleries in such a haphazard way. You might do better using some text and images with your genre galleries to educate your members, or post a reference page with an article describing the expectations. You can't make people read it, though some people will. You're probably a bit limited to what you can actually do with your categories by having a huge body of already-uploaded images. Nevertheless, you can make decisions about what happens going forward.

Just looking at surreal, weird, abstract, and alternative, you have compatibility issues. Lots of people don't really understand abstract art, what it is or what function it serves. Abstract is art more focused on the design aspect of the work - All compositions have underlying abstract designs that give them structure. An abstract work of art would emphasize that underlying structure, often dispensing with the conventional subjects of the work. Abstract art is not about objects, though there is such a thing as figurative abstraction. Even that is not just pictures of things assembled in a way that seems impossible - That's more for the surreal crowd. I've yet to see an online gallery of abstract work that would remain abstract without heavy curation.

Surreal art, on the other hand, is largely (not exclusively) art of the subconscious. It is deliberately and shamelessly weird. So, you can't higgledy-piggledy throw abstract and surreal in the same box as some surreal art is actually richly rendered illustration of objects. Yet even then, the objects may not be the point. See Magritte's Ceci n'est pas une pipe, among other works. That's more about the idea of how objects are translated into images of the object through the filter of the mind. We know the objects we see in images are not the actual objects, but we accept the visual representations. Similarly, one can render a cube, but that cube in the rendering is not a cube. It's a 2d representation of the cube. Even that - Not sure how much of that idea is actually surreal, but there is always some slop at the edges of any genre or movement - We have room to maneuver. Moving on...

The problem with lumping aviation, transportation, and military together is, not all military images involve aviation or transportation. Maybe military should be its own thing. Aviation is a form of transportation, so that can join transportation.

I see I'm the only one with anything to say about all this. Could be I'm the only one who cares? IDK. Back in the day, DA had a lovely, granular image classification system with volunteers assigned to keep the containers clean. They scrapped it all for the nebulous mess that is hashtag hell. Part of Eclipse - Can you imagine naming your site design after a phenomenon that blocks out the sun? Sort of fits in their case.

Anyway, glad to see you're not going that route. Still, simplification must be done carefully, with some nuance and caring for what goes into the galleries. I've no idea what "alternative" is supposed to contain, so I'm not really sure what you should do with that category. But maybe that should be defined or name-changed and refined so that it can serve a useful purpose without making a mess of some other genre. I don't envy you the task. Thanks for your time and attention. Cheers!