I've been using C2's layout editor much more since the introduction of tilemaps. It is pretty great, but I feel that it's still missing a few things. Here are some suggestions:
-'Initial State' property for effects, just like behaviors have.
-A display option for toggling the drawing of effects in the layout editor.
-A display option to show an additional grid where the size of each cel is equal to the project's window size. (An extra layer & 9patch works but this would be nicer)
And the really important ones...
-An option to make all layouts share the same layers and ribbon settings. What if you make dozens of layouts and decide to add/remove/modify a layer? You'll have to do this manually for every layout! It's also inconvenient to have to change the ribbon settings in each new layout. For a metroidvania or any game with lots of layouts this is a pretty big deal. I am uncomfortable making levels without this feature.
-Object bookmarks. This will be great for locating & keeping track of collectibles and the like.