You're looking for simple adventure stories
written in other languages? Or you're looking for adventure stories that have been translated to other languages (simple--for the purpose of practicing reading in other languages)?
I'll just let you worry about the "other languages" part
. Harold Lamb wrote some great adventure stories set in exotic (for the time) places. He's considered by some of the founders of the "sword and sorcery" genre to be the inspiration for the "sword" portion.