No help yet? Ok, I`ll try, but I can`t guarantee that any of my expertise will apply.
This is obviously related to the PropertyHandler portion of the script you`re using. Do you know any scripting yourself? Subclassing PropertyHandler is what makes it possible to Edit properties in Driver and Surveyor. This requires that a script define a "handler" called BrowserRefresh, and the script you are using clearly either has not done so or has an error that prevents Trainz from recognizing it. If you script, you may be able to repair this; if you don`t, you`ll have to use some other script until such time as this script gets repaired.