I have had 2 large salt lamps for years and a smallish tea light/candle holder ; one of the large in my office at work, the other at home along with the candle holder The first year the candleholder 'leaked' but hasn't since, and the other two have always remained dry. I also love the warm glow, but only turn them on occasionally. I've never put a candle in the holder yet, and if I ever get around to it, it would be a battery operated one.

It's just like any other solid material (plastic, glass, marble, ...). If it works, then it's fine to clean it that way. It can be damaged by cleaning agents. But it does take something reasonably aggressive to do so. For what it's worth, you can even clean it with water (e.g. a damp cloth) as long as you don't get any electrical parts wet. It's not as if salt dissolved very easily unless you grind it into tiny crystals or used hot solvent. A little bit of dampness isn't going to do anything. When you think about your lamp, don't think "cotton candy", instead think "block of marble". That'll give you a better sense of what you can use for cleaning.

Warning: DIYer here. I think you may be able to do something less than tearing it out. Assuming the window frame is wood and the wall is drywall, I would start by sanding the frame until the salt roughness is gone, then priming and painting. For the drywall, I would try gentle sanding of the drywall. Then, to repair the drywall, apply a layer of primer, then skim coat with drywall mud, prime again, and then paint.

I‘ve never had one myself. but I literally just a minute ago ordered a salt rock nightlight for my powder room! It doesn’t look like a glowing rock, though. It has a metal cover over it with 2 elk on it, which unlike most nightlights, works well with my Native American bathroom. Saltrock is an interesting concept, though. One I haven’t paid much attention to . . . until today. Helpful emitted ions won’t do much good in a powder room, I’m thinking (LOL), but the nightlight fits, and that’s what I’m mainly interested in.