It would be good for non submitter of set inventories to be able to validate both set parts and loose parts. and if they are correct tell the site that you have found the inventory correct. instead of only having submit change request for when it's wrong. This way we can see how likely that there is a human error in the inventory by how many that has validated a inventory to be correct.
ie if a change request comes after 25 people has validated it, it's more likely that the change request is faulty then all those before him or her being sloppy. or that it's a question of a second inventory version. up to the admin to decide if they want to roll out any change but this give them more facts to build their decision on. after a inventory change is made the QA count should be reseted to 1. (the submitter)
and maybe a QA badge for the set telling how many that has quality approved the set inventory.
As a suggestion, it would be useful to have an additional toggle option in the Inventory Options on the a Set page to "Highlight Lost Parts". Perhaps since missing parts are red, owned parts are green, lost parts should be orange? Alternatively, instead of yet another toggle option, just extend the existing "Highlight Missing Parts" toggle to also highlight "Lost" parts (but in a different colour like orange)?
And since it's related, perhaps either an additional toggle to "Hide Lost Parts" or, again, extend the existing "Hide Missing Parts" toggle to include "Lost" parts as well.
My personal preference would be to extend the existing "Missing Part" toggles to avoid more clutter in the Options menu, but I'm sure there will people who use the existing functions in a particular way which would get disrupted
I actually assumed that this was how it worked from the start, because when you start out with not many sets, it effectively does. It's only once you get multiple sets with the same part that the difference between how "missing" and "lost" parts becomes apparent. I realise there is the "Lost Parts" view under the MY LEGO menu, but that's like an overall summary across all sets. I feel that a quick way of checking which parts are lost from a given set when checking it's inventory list would be useful.