there is no max level, and you just need to make 1 hit on the monster to be able to pick your quest item on the quest monsters. the bosses are no longer "raid boss" status. the only thing you can't do is getting the reagents for mimir's elixir quest if you haven't take the "supplier of reagent" quest on the proper level bracket (5x-75) but there is few sellers that will be happy to hands you those items (from 10 to 20k for each item, you need 100 moonstone shards, 2 quicksilver, 10 volcanic ashes). take care of scammers since those items looks like others with same "inventory skin".
there is no level limits on fate's whisper/mimir's elixir quest (or the one for kamael wich i don't remember the name). the only level limitation is on "supplier of reagent" side quest wich i've already explained the gimmick in order to complete mimir's elixir.
yes, 2 awakened friends (iss and eolh) plowed down cabrio and toi raids in duo party and got the quest item. for golkonda they needed a dd as he was a little too hard to duo.
closing thread and moving to archives. for information: fate's whisper and mimir's elixir quests level requirements are 75+ - supplier of reagents quest is 57-75 levels. the old sub class raids (cabrio, hallate, kernon, golkonda) are no longer raid bosses but quest monsters, meaning that there is no limit to the level of the player killing them and no more raid cruse. you do not need to hit/last hit or even be in a party to obtain the quest item from the chest that spawns after the quest monster has been defeated.