You might be able to determine if the sprite is touching a tile by following these steps:
1) Create a MapInteract object using Engine.NewMapInteract
2) Attach event handlers to it with HostObj.SinkObjectEvents
3) Implement an event handler that handles the OnTouchTile event of the MapInteract object
4) Create a TileGroup object (Engine.NewTileGroup) and tell it all the tiles you're interested in knowing about (which tiles you want to detect contact with).
5) During OnAfterMoveSprites, call MapInteract.Move to tell the object about the sprite's new position
6) Then call MapInteract.TouchTest, passing in the sprite object and TileGroup object. This will cause the OnTouchTile event to be triggered for every "interesting" tile (tile in the tilegroup) that the specified sprite is touching.
This is a woefully incomplete description of the solution, but it might get you on the right track, depending how motivated you are to try figuring that out on your own.
If it helps, MapInteract is the class that GameDev uses internally to detect interactions between the player sprite and the tile interactions defined for the player.
Maybe when I have more time I can elaborate if you're interested in pursuing this solution.
