I did find a couple softlocks when I somewhat recently played this, after watching a friend play it (and if there was a better place to share these links, I'm sorry >.<) (also, profanity warning when viewing) -- https://www.twitch.tv/dragonlord_carter/clip/GlutenFreeBoxyBananaGrammarKing-rvs... one with the iron ball that made it a true softlock, and https://www.twitch.tv/dragonlord_carter/clip/FreezingEntertainingPeppermintKappa... one that I could just pop an Exit item for.
Also, I hope for more birbs, I have a soft spot for the harpy birb style.