First of all, thanks for making this open source. It's a great script.
I'm running a vanilla server that's supposed to replicate the original feel, and as we know the original game only had the option to choose between 2 maps instead of 6.
So I made a fork that only gives you two maps to choose from. Most people would say that's taking away from the QOL, and well, you aren't wrong. But I like it better for my niche case, and it results in more variety.
Only having an A/B logic opens the door for easier controls, all buttons now move between A and B without being restricted to only up or only down. I also tried to take advantage of the simplifications to optimize the script, I'm sure there's more that can be done since this is my first .gsc script.
I'm sure you'll dismiss the 2-maps-only idea, but there's a change I made that you might want to consider: the text in the top right corner now shows total votes/players. Your version shows the index position of the cursor, which I don't really see the benefit of.
Another thing I did is select a random map in a tie instead of always picking the first one.
Link to the fork with more description: https://github.com/cachho/iw5-mapvote/