Dui, ni shuo de dui
Actually, a few droplets of water in the spindle motor should have no effect. The motor wiring is made of magnet wire, which is coated with a very resistant resin, so waterproof.
The only non waterproof part is at the top, where the brushes are located. That where you should avoid water. But here again, as long as you do not pour gallons of water on it like a moron, should be no problem. XD
I would be more concerned about the spindle bearing rusting than electric issues. Just for safety: ground your water bath to the earth wire of your main plug, in case there is any problem. And avoid touching the water while the spindle is plugged, always cut the power first. Just common sense.
But anyway, just use the CNC to cut a shield out of wood, it’s really no rocket science, no need to overthink such an easy issue.