Right now, the brackets in Musescore are rather lacking. It's an all-or-nothing affair, where you can only have brackets on all of a particular staff for the entire piece or not at all. When combined with invisible staves, this makes for disaster, especially since brackets cannot be made invisible. What would make brackets far better to use would be the following:
Give us the ability, when adding brackets, to choose which staff the bracket starts on and which staff the bracket ends on. This should remove most of the problems that I've mentioned, if not all of them.