We have had some monstrous deluges here. I use to go out and pre-backwash in anticipation (yes, I'm a jackass too...), but some of our storms, especially in the spring and fall will still overflow a pool that is drained a little from the get-go.
Here recently it actually has overflowed several times regardless of my better intentions. And I learned one key thing... The overflow doesn't really hurt the pool. There it is, plain and simple.
What you do need to watch out for is erosion. Water spilling over the edges of the pool can erode the dirt below and then you can have a pool failure. This is how the levees failed in NOLA from Hurricane Katrina. They were strong enough to hold back tides at war, but a little trickle over the top and all the sudden the earth eroded and there was nothing to hold up the levee - WHAMO!
Rather than obsess about the pool level and overflow and storms and stuff, I just make sure I have a good thick bed of pea gravel surrounding the pool to reduce the pounding effects of the water flowing over.