The comments with personal experiences is the most informative part. It's no surprise that passing a single test a single time is not an assurance of continued proficiency, but it certainly can be used to exclude people who might otherwise drive wages down.
I wonder if vertical LED strip lights spaced around the cockpit that illuminated sets of individual LEDs would be effective at establishing an artificial horizon without requiring the vertigo inducing turning and tilting of the pilot's head that looking down and to the side a conventional instrument panel can. Advantageously they could be in the pilots line of sight almost all the time, reinforcing their reliability and calibrating the pilot relative to them against external cues. Color could be variable to align with lighting - red at night, some other color in the day time. No need to provide expensive focus optics as a typical HUD requires.
Example - one strip up the right side, one up the left, and one in the middle would provide 3 points defining a plane parallel to the nominal Earth at that point. Maybe add some offset for all three to account for pilot eye-height?