My sewing room windows in my old sewing room were open pretty much 24/7 unless it was a really hard slanting rain. Never had the least bit of trouble with my machine, and it was set up (in a table) directly in front of the main window. My PC is still in that same room, not one lick of trouble there either. I'm a very early riser and often are on the machine by 3 or 4 AM on a weekend - never seen dew on my machine, or on anything else indoors, not even when we leave the big back slider open all night, which we often do. So it really doesn't seem to be a concern where I live.
If excessive humidity is that troubling to computerized machines, how does anybody in a place like like FL or HI sew??