Maybe it helps to know that FME inspectors listen to the fme_color and fme_fill_color parameter. You could set up an attributeCreator or attributeValueMapper to set the fme_color and fme_fill_color. Both can be set with an transparency setting I believe. A fme_width attribute could give it the last push.
Working with these attributes would mean that you can give attributes the styling that you want at the start or your workbench and all inspectors listen to your settings.