I guess one such test could be devised.
I have a theory/feeling that allmost all the issues of the device come from the faulty battery. Maybe including the touchscreen issues (where I've noticed that the touchscreen is more accurate when it's plugged in).
The battery seems to have a weird chemistry where it discharges non-linearly and I think sometimes just doesn't have enough power at all, that's when you get into the coma behaviour or the reboot loop.
While it's true the the Android core could be optimized more for the power consumption, that's just one angle.
I'm afraid the other is the faulty battery
At least I'm sure I have one, and from the data you're showing (that looks just like mine) I would say you do too
(