The game seems to expect a particular solution even when there are multiple possibilities of forming correct words. For example, I tried "peeks" & "bully" but the game only accepted "peels" & "bulky". This is frustrating, as one has to "mind-read" the game.
Another thing to improve is to reduce the frequency of plural forms. Plurals are just a cop-out to turn four-letter words into five-letter words. ;)
In Worldle you need only guess one word. The player can do whatever they want to get there, but there is only one valid solution. Having two (or more) valid solutions to a game, but only accepting one of them, is unfortunately a recipe for frustration.
The equivalent would be if Worldle made you also guess each intermediate word to get to the solution.
Another thing to improve is to reduce the frequency of plural forms. Plurals are just a cop-out to turn four-letter words into five-letter words. ;)