I agree, without bypassing the RLU, there is no way to know for sure if it was lighting the wrong led's.
on a normal incandescent bulb, the RLU will sense if the low beam (or high, if switch is in high position) is intact and flowing current. if it is, all is normal. if the filament is blown, (no current flow thru that filament), it will switch to the other filament, so that you have SOME form of headlight.
with an led (which draws a lot less current), it will get confused and rapidly switch between the 2 (high and low) circuits.
also, a standard incandescent headlight bulb under normal operating conditions, only lights either the high beam filament, or the low beam filament (not both at once). Flash to pass features will allow both the be lit, presumably for a short time only. However, I have driven down the road for miles with both lit on an older car I had, because the headlights where about as powerful as a single small candle
Many led headlight bulbs are not properly focused in many headlight reflectors, due to the different placement of the actual device that emits the light (the led itself), is in a different postion, and has different light emission patterns than the incandescent filament. that can cause improper beam formation as it exits the reflector and lens assy.