I bet you’re just not looking at the CustomPage page. I tried your code and was confused for a second because it’s a bit hard to tell. Click on the CustomPage label.
Also, you know you can create your parameters using the Component Editor, yes? You can still set the menu options the way you are doing it in this code.
For simpler lists I’d use the component editor GUI, but this is actually a drop-down of easing functions and there are a lot of them. Simpler to manage in code.