If you break open a hole in the wall of your current dwelling, that faces the rain tower closest to you, your actual coverage will improve.. of course, only if you do not have another building between yours and the rain tower breaking line of sight..
It's not possible for the coverage map to take into account the other factors that affect the quality of your connection.. it's just that, a coverage map and not a connection quality map..
Disclaimer: I am not actually advising you to break a hole in the wall, simple stating that it would improve your connection..