1) It isn't clear what is clickable and what isn't, I feel like I should be able to click on the blue comment badges and see related comments (or is that # related to requested change count?)
2) Secondarily to this, when I click on a dom element, it automatically defaults to the inspector tab, when I feel like this gets too deep for a product owner just wanting to make comments on a section
3) I am not clear on what the difference between a red highlight box around elements and a blue one means
After looking at it a few minutes more, other than the comments above, I think you are thinking about it in the right way. I feel like there are levels of depth/advanced features that should feel more progressive -- right now it seems like feature overload on that first view. Maybe the default view is just something where you can click on dom elements and add comments, the second "tab" is "Request Markup Changes" where there are no comments -- when you select an element you can make markup changes with the advanced inspector and there is a history of those, and then you might could even get rid of the "screenshot" view. Or maybe mix the screenshot "highlight area" functionality with the first/non-dev oriented commentary tab/view
Sorry if that last paragraph isn't concise, I can rewrite it better if some of it wasn't helpful. Also this is all obviously just my opinion
Edit: I made edits above ^ Edit: Last edit. I also notice the UI/UX seems a bit different on your landing page demo vs what is present in the demo link. I personally kinda like the comments having their own dedicated space to the left of the page, then you could toggle the advanced inspector tab on the right, in and out cleanly. Not sure if there is a way to change the comments to the left currently, or that was a previous build. But I feel like it addresses some of my commentary above.