In the function BIS_fnc_randomPosTrigger you have the ability to just call it by "["anyMarkerName"]call BIS_fnc_randomPosTrigger;".
You will then get an error because of following code:
_tPos = [_this,0,[0,0,0],[[],objnull,""],[2,3]] call bis_fnc_param;
//--- Marker
if (typename _tPos == "") then {
_tArea = [markersize _tPos + [markerdir _tPos,markershape _tPos == "rectangle"]];
_tPos = markerpos _tPos;
};
_tPos given as string will allways return false for the check (typename _tPos == ""). It should be (typename _tPos == typename "") in order to work properly.