Since Map Finder is a feature of the HOF Mod, I think you can assume that it is legal.Is this legal in HOF games, given your playing with knowledge of the map your using?
Seriously, the only information you get on a map is what you can see when you generate the map. (i.e. only visible tiles) All Map Finder does is take the tedium out of generating a lot of starts looking a good starting position. It levels the playing field for those that don't have a lot of time to do that.