The front window is always window 1. I tried to specify the window containing "- Transform" but this didn't work (maybe because it's a floating window). It doesn't really matter though, as you'll only be using this when Transform is at the front.
Get the trial of UI Browser. It's being discontinued soon, so it might end up open source (free). If you don't want to wait, there are other ways to get a UI Element path for free, like THIS.