So it seems that db-LB is baked into i18n-abide as the real debug locale the setting for debug_locale in i18n config just maps to that. I've added that as a locale (It needs to exist to work) but it's ignored. it_CH as a locale has been removed from this as it's not in webpay. 

So now you'd use db-LB/foo/bar to see the debug output in the app or use db-LB in the headers.