Seems to be a fork.

https://ejje.weblio.jp/content/higgledy-piggledy
ひどく乱雑な、めちゃくちゃな

雑然	98589	  
雑然とし	75205

"aligning" with suggested changes to 雑然とした (apologies, all the refs went over there). 

Recommend the current 雑然とした entry be deleted.  Instead, copied a "とした" note from another entry.   Not sure how I feel about this. (Well, in fact I think it would be useful if these notes were used *more* often, but I think most する [adv-to] entries that could have such a note do not, so...).

I moved "messy" further back because it is ambiguous in English (can imply filth, a messy plate, or a room with food containers everywhere).  Pushing it back down the list surrounds it with terms indicating that this is primarily about disorder. 

I'd never heard the term "higgledy-piggledy", but that's on me. I'm surprised at how common it looks googling around.  Even so, I don't think it matches the tenor of this term.  Perhaps it would be a better gloss on something like めちゃくちゃな? (suggestion found on weblio). I'd be cautious though, as I think 雑然 and めちゃくちゃ are universally comprehensible (as are all of the glosses above), while higgledy-piggledy is maybe idiomatic, and a Japanese person maybe shouldn't be encouraged to use it as a J->E gloss without warning.

If you are all confident I'm the only one who doesn't know this term, then I understand if you put it back :)

@@ -13 +13,4 @@
-<gloss>messy</gloss>
+<s_inf>often 雑然とした, etc.</s_inf>
+<gloss>cluttered (e.g. desk)</gloss>
+<gloss>jumbled (e.g. thoughts)</gloss>
+<gloss>messy (e.g. room)</gloss>
@@ -16 +19 @@
-<gloss>higgledy-piggledy</gloss>
+<gloss>chaotic (e.g. lifestyle, atmosphere)</gloss>

daij, gg5, prog, ウィズダム

Not a noun.

@@ -11 +10,0 @@
-<pos>&n;</pos>
@@ -14,4 +13,4 @@
-<gloss>disorderliness</gloss>
-<gloss>confusion</gloss>
-<gloss>jumble</gloss>
-<gloss>mess</gloss>
+<gloss>messy</gloss>
+<gloss>untidy</gloss>
+<gloss>disorderly</gloss>
+<gloss>higgledy-piggledy</gloss>