>>48560977There's really no way to search for characters/pokemon in the background of art. Some people may compile lists of them if you're lucky, more likely for the waifus, but really it's just down to you to spot them.
As far as JP vs EN, there's a few different sides to it but it's mostly just preference. JP is typically cheaper, has higher print quality (pic related), and gets a lot of exclusive promos, but most people still have a preference for their native language. If you only care about getting the art for the lowest price, Korean is also an option but I'm not sure how the print quality compares.
