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The constant voltage regulator doesn't do anything with the dash lights. So you can rule that out. It just runs the gauges.
The fuses do affect the lights though, specifically the one in the middle labelled "Inst. L.T."


Also, the fuse box connectors can get dirty and rusty over time so you might want to clean them off too. Disconnect the battery first just to make sure you don't short anything out while you're cleaning.

LEDs can be a little finicky. You might want to find one good old bulb and put it in while you're testing just to make sure you're not having a problem the LEDs. The LEDs dim differently than the old bulbs and they might not work at all if the headlight switch isn't rotated all the way to the left.

IIRC the power to the lights goes from the headlight switch to the fuse to the dash lights so it's possible that your headlight switch is bad, but definitely fix the fuses first.
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