Oh my. Great job!
Yes you can cut it back lower down. I wouldn't cut it to the ground though
Look at it this way. You have a ready made very nice large plant.
If you cut it back, repot the entire top, or cut in thirds, and repot everything in a much larger pot like 10-15 gallon. Install a hefty support (this can be a wood plank of lumber untreated with chemicals) from the start. All the stumps will reshoot, and in the meantime, you have that group of large top cuttings to carry on.
You don't have to do anything silly like trying to root in water
All the adventitious roots there are good. Just bury the lower ones and they will automatically form soil roots