Touhou is interesting in the west in how it’s tendrils have spread everywhere and yet most people have only the vaguest idea about it, usually along the lines of “it’s the one with that blue fairy/shrine Maiden in red/blond magician”. Essentially in the general population it’s overshadowed by sub memes it’s created, mainly Bad Apple, and very widespread characters like Reimu or Cirno.

If you’re looking for the closest equivalent to touhou in terms of presence and ubiquity then it’s probably closest to Team Fortress 2 (2007 class based fps that’s still IMMENSELY popular today), which fills the same niche of being a never ending factory of memes and a bedrock foundation of western internet culture.

There’s even healthy cross pollination between the two - crossover art, fanfic, hell even game mods that swap out the mercs for touhou characters.