Safe to leave eggs in water overnight?
Go for it. Eggs in their shell are pretty sturdy. Technically, a very small amount of water will be absorbed by the eggs, but unless you weighed them, you probably won’t notice.

I do have a small caveat, though: eggs are susceptible to smells, the chalky shell is pretty permeable. So if your tap water has a lot of chlorine or other strong tasting stuff, it’s probably not a wise idea to let the eggs absorb that. The same is true if you live in an area of the world where tap water may be contaminated by bacteria. In such a case, you need to boil the water first before adding the eggs.

In short: if the water is good, no problem.