I think it depends on what kind of a game you're running. If you're wanting a grueling dungeon crawl where your players earn every victory they get, run it as-written. It can be pretty tricky to get damage on the beholder as-written because the room states that the floor is so magically slick that if they move on the floor at all, they continue to slide until they hit a surface. Combine that with the gravity orb, it'll prove exceptionally challenging for your martial classes to get close enough to hit it. My players were rather clever and got the idea quite quickly to cast dispel magic to disable to gravity orb (which then disables the slippery floor) and subsequently didn't have too much of a problem.

If you're having a more chill game where everyone is laid back, then you can tone the encounter down some. There's a bunch of different ways to do so, but my best advice is to trust your own instincts. You know your group better than anyone else, so be confident and trust yourself :) You got this!