Just for information, I was recently updated from the android 7.1.1 beta to the final version, and it seems like some of the bugs reported above are no longer happening.
The minor visual glitches are still there when you open settings whilst having the keyboard open.
Number 2 seems to have gone completely.
The gboard bug definitely still happens. Seems like it's related to when a word is automatically corrected. Gboard seems to add an extra space after the word when it autocorrects it, which is probably overriding your handling code for the enter key.
Number 4 I haven't experienced since the 7.1.1 final, so hopefully it's gone with the os update.
Copy pasting multiple lines seems to not allow me to select more than one line now, so I can't replicate the issue unfortunately.
The last bug I can still replicate by creating enough lines to fill the whole screen, then scrolling to the last line with the keyboard hidden and tapping on the last line. The cursor seems to get hidden behind the keyboard when it appears. I would be expecting it to scroll the line into view.
Fixing the gboard bug and the last one on the list, together with bold and italic formatting would make the app pretty useable for me.
I've already decided to make the jump from workflowy due to the mobile web on dynalist being better than their android app, as well as a few of the other features (links ). It's useful enough to me to be worth paying for already.
I'm sure there's probably a few more things I could stick on my wishlist, but I'll leave this for another day.