"Be respectful. Anyone sharing work is making a contribution, however modest." -Perhaps I could have phrased this a bit better, but the design in its current state makes it hard to take it very seriously.

"Ask questions out of curiosity. Don't cross-examine." -N/A

"Instead of "you're doing it wrong", suggest alternatives. When someone is learning, help them learn more." -My suggestion was to hire a designer, which I hope they follow. However good an app is, without good design a lot of people won't take it seriously or consider it a professional product. This especially applies to non tech people, which is most people.

"When something isn't good, you needn't pretend that it is. But don't be gratuitously negative." It's not like I called it a piece of crap. The app may be fine. But at the same time I'm going to call a spade a spade. The current design makes it look extremely dated.