Oh yeah, he's definitely a kid classic character that hasn't been properly introduced to the American people for sure. There's a lot of context tossed out there when the character is only known through funny internet videos about toilet training. But several years back when someone showed that to me and we saw it in a Korean grocery, it was hard not to make the connection.
I know about Shimajiro as well as every other Japanese toddler series. I've seen a few episodes in Japanese. Not all of them are about using the toilet. For example, one was about Ramurin helping children at the playground, and another was about them trying to help a local farmer enter a pumpkin contest, but some evil cats were trying to cheat. And as a prize for cheating, they got toilet paper. And an episode I saw an ad for was about Shimajiro sleeping over at his school and thinking there were ghosts. Oh, and aside from the toilet training episodes I saw as a kid, I saw one about crossing the street where he had to go on some train to get somewhere, and the evil cats were in it. I've also seen Shimajiro cookies at grocery stores, and knew it was a toddler show since I was a child, when I watched that, Tamagotchi!, Pokemon, Tokyo Mew Mew, Ojamajo Doremi, Mermaid Melody and Pururun! Shizuku-chan in Japanese.
Also, they did dub this show. On the comments of the "Shima to Land! Island" opening theme, someone said they owned a VHS tape of it in English. A check of their profile said that they lived in Australia. Then again, Australia has a lot of missing dubs, like the Minky Momo dub "The Magical World of Gigi" and the Cloverway versions of Ojamajo Doremi and Crayon Kingdom of Dreams.