Wow, very detailed post!
I've always thought the screen on my Teclast T39 had very poor viewing angles. In fact it looks like a portrait aspect ratio screen, that they're trying to use in a landscape ratio... Which might explain it.
The brightness varies so much from left to right that you can't view up close, so you have to hold at arms length and at a certain angle
I haven't had a flickering problems though... Maybe just your files?
I would expect the Rockchip version to have an identical touch screen but obviously not
