That's an excellent initiative GeeVee. I'm in Western Australia and haven't heard anything about it. Coloured ribbons on a Kingdom Hall wouldn't mean anything if the public didn't know the significance behind it. Given the publicity in your hometown, it's a fantastic idea.
This will be really embarrassing for JWs. They won't know who's put them there but because it's not an initiative directed by the Watchtower they'll have to remove them, therefore demonstrating that they are showing a lack of support to those abused. That may just help to wake up some sleeping JWs.