I would sand down the sharp edges a little just as a safety measure. I've never seen anyone post anything about their snake getting cut on them, but that's not saying it can't happen. Keep in mind, that if you aren't planning on separating them soon, you will need to provide 2 hides on each side or the snakes will choose security over comfort and not thermoregulate. Your snakes aren't snuggling in the one hide, they are competing for the best spot.
I don't see any reason to change the substrate yet. Your first order of business should be to get your AccuRite and probe positioned properly and get the heat under control before one of your snakes get burned. Then, if necessary, change out the substrate, depending on what the humidity is doing.
The main reason I don't like the log hides is when poo or urine get on them there is almost no way to get the smell out of the wood...