Hi
Some comments.
“I’d like to set it to pop up right after the content, so before the comments.”
For that, Yes, choose “Element” triggering, leave the scroll% to 100% and insert into “element” field value: #comments
Then scrollbox appears just when comments part starts to appear at the bottom of screen.
If you want scrollbox to appear same time with new comment input fields (below the comments usually), then for that the element value is: #comment
Those values are the same for most (all?) WP themes.
“.. on my phone, once I clicked inside the form to input my email address, my keyboard popped up and covered the form so I couldn’t see what I was typing.”
That keyboard floats over the browser as separate application and unfortunately browser is not aware that something is blocking the view now. That’s why the scrolling happens behind the keyboard. So i’m afraid that there is nothing much to do about it. Myself I have used to check the “hide on mobiles” checkbox because I don’t personally like such boxes on phone at all.
Perhaps the plugin should allow user to choose such option, that on mobiles the scrollboxes appears always on upper edge of the screen? However, this doesn’t always guarantee that fields remain visible (phone can be in landscape mode and scrollbox can be tall). Another option maybe could be, that on mobiles scrollboxes can be scrolled after opening together with page. I will think about it.