In my experience with the LttP randomizer, nothing is really unbeatable. There are some situations that you'd absolutely never run into during a normal session, but a lot of the tricks to get past them aren't super difficult to pull off. The logic is such that every game is technically beatable, like you're never going to NOT get an item you need, or enter a dungeon that somehow doesn't have enough keys to progress through. Items can be real tough to find if you don't know a lot of the places to look, too. I've had a few games where I didn't find a sword for a really long time, having to make do with bombs, the hammer, or the Cane of Somaria.