Thank you for playing! :) I found the teleporter idea really crucial, as it marks an option to me as the designer to prevent the player from snatching up as many keys as possible without much thinking about it. If you do this and walk into a teleporter, most of the keys will be gone, potentially rendering a more complex puzzle impossible. For level 6 this is hardly the case, but it's easy to imagine more complex puzzles that require you to go back and forth between two teleporters and carefully think about when you pick a key up as well.
Not quite sure however what you're referring to regarding the animation. Have you played the HTML5-verison? Might be due to that, the web export of the Godot Engine seems to have quite a bunch of unresolved issues... But I'm quite happy it worked at all! :D