I posted a more recent MA terrain guide than that in 2018 but I never got it stickied for some reason, here's the
link.
In general an MA map needs to be balanced for all three countries, have the correct field distances, have a workable capture path for all fields and include a working strat system that's not too vulnerable to attack. You shouldn't have a layout where one team goes "Oh ****, we got the South side again!". My advice is if you are thinking of doing anything unusual in an MA terrain, i.e. something you have not seen done before in any other MA terrain, then PM Hitech and get his approval first before spending a lot of time working on it. Trust me, I speak from experience on this.