It is clearly stated, what BAI can do and cannot.
Setting 1 will allow only units that directly see your troops, to aim and fire.
Setting 2 will make enemies attack only units, which are revealed this particular turn. E.g. when one unit comes close and reveals your positions, pretty much like player, BAI then can attack whenever and however it thinks better for getting to the winning condition. Getting closer to LoS fire, or from deep dark no-LoS, or by melee.
Ok. Now. As far as can get, you want something between setting 1 and setting two, where only part of no-LoS enemies can shoot at you?
If so, go ahead, visit BAI subforum and propose it. Xilmi is opened to suggestion and pays attention to reasonable arguments.