There seems to be a problem with the item ids in the mod. With this new setup, the ids will start at the highest id for blocks and items and count down until there's a free id spot.
So far all the blocks are being added to the creative tab, but the ids aren't.
There doesn't seem to be any indication of whether the items aren't being added to the creative tab.
There have been problems with other mods I've played where the id conflicts aren't caught and thrown as an exception, but blocks and items replace each other instead.