Maybe Luke hallucinated a second Sun as he was dying from focusing so hard.
The novelization suggests that the Ach-To scene begins near dusk, continues overnight, and ends with the sunrise. If that can be realized well and without making the scene difficult to see, it could be a good way to imply a longer stay on the planet. Especially now that the 16-hour ticking clock has been removed. Yeah they’re in a hurry, but that specific element is gone.
That’s exactly what I always thought until I looked it up on Wookieepedia just now! I mean, heck, I even double checked the “Rey wakes up” shot, and I only see one sun. Maybe I miscounted.
Although, it does make you wonder how TROS’s official story goes through an entire night cycle in, what, 10 hours? Alien planet, I suppose.
The tricky thing about dimming this scene would be, like you mentioned, Hal, making the light sources still effectively “generating” light. Luke won’t just have to be (less) blue; he’ll have to literally glow. The fire, the sun(s)…it might be tricky to pull off convincingly.
EDIT: If we do want to go this route, I think we should ignore the novelization about the scene lasting from dusk to dawn. I think it would be more visually intelligible to simply go from nighttime to daybreak. The scene is only a few minutes long, and I’m worried it will feel oddly paced to try and display an entire night in those few minutes. (Plus, it feels more symbolic to me.)