If I were to tackle a B5 reboot, I’d cut down on the amount of extraterrestrial species. Keep the core races like the Centauri and Narn, of course, and some of the more exotic beings like the pak’ma’ra, but dispense with the background/one-off aliens whose presence adds nothing to the universe.
I think “cut down” is the operative word in general for rebooting that show. Part of its genius throughout, but especially in the first few seasons, is trying to show how “life goes on” on the station despite the massive events other places in the universe. I do like that a lot as a comment on how the average person is able to ignore important events as long as they’re on the other side of the world.
That said, what they choose to focus on instead as their plot-of-the-week is often far less interesting. I think you could retool those stories to be much better.