Thanks for sharing your feedback! I've just sent you an email with a couple of additional questions about your expectations from the app.
It looks like the website works in Safari on the iPad. Maybe that's enough? Aside from offline access/editing.
+ 1 on IPad app, it's really needed
Is it best practice to use the RTB app or a browser on iPad pro with pencil? And for the app do you need beta testing and/or specific types of feedback?