[ksa]

macro1 += "WAIT SECONDS=3" + "\n";

Пробуй так

var max=10;
var min=1;
var tim=Math.floor(Math.random() * (max - min + 1)) + min;
alert(tim)
var macro1;
macro1 = "CODE:";
// ...
macro1 += "WAIT SECONDS="+tim + "\n";