I discovered an event that was added at some point after I implemented editmode, net.minecraftforge.event.world.BlockEvent.PlaceEvent. This will prove to be much more secure and accurate to use for checking if a block is placed or not than the player interact event. Changing the event will fix the issues where placements costs grist even when the blocks fails to place. (Like when placing sugar canes without any water nearby) The grist cost problem might also show up to normal blocks (until I've fixed this issue) if another mod uses that event and cancels it. I'll be fixing this in the 1.7.10 branch too.