The conclusion appears to be:
In other words, since Kess, Dissident Mage let you cast instant or sorcery from your graveyard once per your turn, you can technically cast Adventures from the dead as well. And, if you have a sac outlet like Ashnod's Altar/Phyrexian Tower you can sac an Adventure creature and cast it again from grave. When we return those creatures from their respective Adventure, we could pay extra for Equilibrium to bounce another Adventure creature back to hand for usage, somewhat bypasses Kess's restriction.Now, under the reworked 601.3e, you just check legality based on what you actually want to do, rather than go through those hoops. Makes a lot more sense.
Example: Garruk's Horde says, in part, "You may cast the top card of your library if it's a creature card." If you control Garruk's Horde and the top card of your library is a noncreature card with morph, you may cast it using its morph ability.
Example: Melek, Izzet Paragon says, in part, "You may cast the top card of your library if it's an instant or sorcery card." If you control Melek, Izzet Paragon and the top card of your library is Giant Killer, an adventurer creature card whose Adventure is an instant named Chop Down, you may cast Chop Down but not Giant Killer. If instead you control Garruk's Horde and the top card of your library is Giant Killer, you may cast Giant Killer but not Chop Down.
Kess is known to be a spellsling value commander, creature is usually the minority of the deck, though with the new Adventure creature we could now have some board presence, aiming for more longevity. I don't mind saccing the said creatures for mana then cast other spells also. I wonder if this would be a fun alternative approach for her.