Okay, that makes sense, and good information!Again, the inverter board doesn't know or care whether it's being fed normal or inverted video; it will invert anything you feed it. If you feed it inverted video it will output normal video, and vice versa. In the case of a direct-feed setup from a Nintendo boardset, you would be feeding it inverted video and it would output normal video, which is what you want for the RGB-to-NTSC converter and the VCR.
With a Nintendo boardset, when going to the Sanyo monitor (as opposed to an RGB-to-NTSC converter and VCR), you do not use the function of the inverter board (you use the pass-through header or bypass the board altogether) because the monitor's chassis (i.e., the main PCB of the monitor) also inverts the colors by default, so if you did that there would be two instances of color inversion in the same chain, which would cancel each other out, leaving you back where you started, i.e., you would see inverted colors on the monitor.
To summarize: the Sanyo monitor's chassis inverts whatever is coming out of the color inverter board, but an RGB-to-NTSC converter and VCR do not invert anything.