Hey, welcome!
Currently you'd have to put some other solution in front of Sandstorm to get fail2ban-like functionality. I don't believe Sandstorm itself logs anything you could look at for most authentication failures as in many cases they are punted out to other authentication providers, but depending on your login method of choice you probably have some options. (For instance, I use LDAP, so fail2ban could monitor the LDAP service's logs.)
For file versioning are you looking for like an automatic ability to revert to older versions of grains?
Unfortunately right now the "features coming soon" are all more of "hopefully someday" to be honest. Right now the tree of capability sharing all exists in the context of the database, but it would probably be a somewhat painful process to extract that data into something visible if you needed it. Ideally it'd show up on the "Grain Settings" tab with has room for more detailed information than the sharing dropdown. Group management will hopefully be something addressed more heavily in Tempest than it was in Sandstorm. There are some concepts around "keyrings" to make it easier to share capabilities between people.
I know of at least one or two experimental projects involving bridging desktop screens or screen sharing into Sandstorm apps, but nothing that is production-ready. I think there's a deeply untapped market of apps and tools that could be integrated into Sandstorm's model but in many cases, nobody has even tried! The powerbox is one of those things that came very late in Sandstorm's more active development period, not a ton has been built on top of it despite it opening up such a wider array of possibilities.