I have English as the base language but I also support English (UK) which defines a few UK specific localizations but should fall back to English for everything else.
The way I have it now, all my fallback strings are in "New" state in the UK localization, ie they don't have a UK specific string. This actually works, but UK completion is at 5% and I can't find a way to tell it that the rest are OK to be taken from the base language. By keeping a lot of "New" strings, the tool won't be helping me when I add more strings to the base language.
Marking those as Reviewed creates a blank string localization which is obviously not what I need.
BTW if marking as reviewed would help here, it would be a pain because it has to be done one by one, I can't multi select.