Simple question: if you exile a buyback spell, say Capsize, with Living Lore , and "you can pay additional costs" according to Living Lore's Gatherer page, can you pay the buyback and end up with the formerly exiled card in your hand?
Buyback costs are additional costs (which still apply to a spell even if you cast it "without paying its mana cost" [C.R. 117.9, 117.9d]) (C.R. 702.26a), and as a spell with buyback resolves, if the buyback cost was paid, that spell returns to its owner's hand instead of to the graveyard, no matter where that spell was cast from (C.R. 702.26a).
This works. Because Living Lore doesn't effect which zone the exiled spell goes to afterward like say Flashback it will go to the GY like normal and because buyback only cares about the spell going to the GY afterward in order to move it to your hand instead it function like you would want.
Living Lore and Buyback