How Do You Traverse Composite Sprites

They're not like simsets where you can use getCount() and getObject(). I see that there's a getSpriteCount() but none of the selectSprite*() methods work with by index. Am I going to be forced to keep sprite ID's in a simset for procedurally generated sprites? Edit: Also, why does selectSprite*() echo a warning in the console when it doesn't find the sprite, isn't that the point of the function returning a bool.