The above quests automatically complete if you have 4 of the required item, It does not consume the items. meaning you can just get 4 diamonds, get the reward, throw them. pick them up, repeat.

they should be switched so that they have to be submitted.

This is not an Ex Deorum bug. Go report it to the mod pack author

Sorry about that, I thought I was on the modpack developers page ! not sure how it ended up here