Like an idiot, played most the game (4/5 skeleton pieces found) and went away for a bit, came back and I can't remember how to teleport to frogs, pressing C like the upgrade instructions say doesn't work.
What I'm fishing for is whether you still have the item or not, and didn't quit the game without saving since you got it. Because I can't really think of anything else that would cause this item to not work.
If you've checked and are 100% certain that you have the item, could you email me a copy of your save file? You can find my email on my itch page.