How about instead of being forced to get all 6 lantern colors (considering some are based on pure luck and are just annoying to get to begin with) 1 lantern is required to start the fort plus the ritual skull and then every lantern lit after that before the fort is activated, determines the forts difficulty. So each lantern lit will add an extra 3-5 waves before the final fight and also each lantern lit will also determine what loot spawns in the vault as well as rarity.
For example, 1 lantern lit will only be 5 or so waves, but it will yield the worst loot in the game and not a lot of it, and if you light all 6 lanterns you get the current loot (maybe 2 Athena chests) but your also doing 30 or so waves of skeletons plus the boss fight.
This would allow people to actually complete the fort and complete the legendary commendation for it in a timely manner, but also tempt the greedy pirates on the sea with all 6.
