I see, that is indeed unreasonable with it being that hard to implement, perhaps something else entirely? Like an item that just creates liquids on demand. For example making a pump that just creates water or lava or honey. Of course I have absolutly no clue as to how hard that would be to implement.Thanks for giving Terraria Tweaker 2 a try!
About liquid duping: I do miss that as well, but as for restoring it, well, unfortunately - no. The classic water/lava duping techniques were a byproduct of a bad, complex water system. Recreating those duping techniques requires replacing the existing water system with the old one, which would be an absolutely enormous burden for a very minuscule gain. So, as I'm sure you can guess, that isn't going to happen, I'm afraid.