The best way to use broadcast safe is with the “key out unsafe” option. You place it in an adjustment layer, switch it on, and scan through the comp for any keyed out bits. If you find any, adjust hue/sat or levels until they come back, then switch off the Broadcast Safe effect for rendering.
Make sure your comp’s background colour is something bright that you can see, at least for this test.
As for yellows, to make them safe, use hue/sat to make them a little more orange. Tip from Frank Capria.
Steve