Suggested quest order would be something completely different from this list, when all quests under lvl 6 without "strong" or "group" flag is completeable by lvl 2-3 character.
Recommended level seems bad too due to quite different build power. One could beat Ark on hardcore on lvl14, I did on casual on lvl18, and someone can't on lvl24. So I think it should be part of build guides.
Since most difficulty come from "strong, group, etc." and elemental damage, user should be most aware of it, not the level. Perfect example is " where did I put my sword" with a ton of poison damage. No player can get resistance or health to the point of lvl 6 to fight the ghouls. I see this resource mostly as a hint for the user to know better how to prepare to certain quest.