The fix for will go live with GU 42 which I believe is the 29th of January. It should fix all the issues with all three language quests including those who did not get the devliery quests updated and those who accidentally deleted the books before reading them.
Those who deleted the book before reading them will be able to complete the second quest and get the language.
Those who did not get their first quest updated should be able to return to the npc for any of the three language quests (Froak, Di'Zokian and Sathirian) and get those quests updated and receive the rewards and exp.
LINK
(Kander) Re:Di'Zok Language quest "Locate The Legate" is bugged.
