If I'm refining opaque, I fill ding holes and cheat lines with Bondo glazing putty. Works fine.
I have seen one guy mask repairs and shoot Gibson cherry over it. It requires artistic flair as you have to use artists techniques to paint a faux wood grain and tone to match it with the raw filled wood. The Gibson cherry has a stain wash but the cherry color is just see through tinted lacquer. Multiple passes deepen it, and you could cloud up a pass to help. The guy I saw do that fixed a red Epi that got bashed. You couldn't see it afterwards. He's dead now.