The idea is cool. However, the watch would essentially never be correct and therefore no one would want to download or use it. Yes, you could make a cheat sheet so that someone would be able to read the watch. This person would also have to memorize what all the conversions are to figure out what the real time was.
I am not trying to be rude, just be honest and let you know why this would not be worth taking the time to make. You are on the right track with ideas of making something different. For example, I just recently finished my watch face of an analog clock that runs counter clockwise.
You would not need a cheat sheet if you just ignore the hour ticks and focus on the hands instead. But still... why would anyone use such a watchface? It would make more sense to create a 24h watchface. I think I'll do that, actually... :)
