Perhaps not WAS as this can be searched for and found in the grid & could become its own red herring. Having just the W would probably have worked for me, but I'm not sure if it could also be similarly misinterpreted.
It's currently the only puzzle where one of the leftover letters is hidden, so amending that might help (by that point I had come to assume this was one of the rules.)
I'm conscious that I'm just one person & a lot of players presumably got this without the nudge. On the other side of the coin, I figured out the letters and numbers in v1.12 without any need for the new hint. Is there a case for formalising the two-tier difficulty system introduced by having 1.12 & 1.13 both available?
(Re: the treehouses, I won't go into specifics as this isn't the venue for The Witness spoilers, but I mean the early puzzles allowing for an internally consistent yet incorrect understanding of the rules.)