Also, you could forego on the localization of the quest name as you could use the following :
C_QuestLog.GetTitleForQuestID(questID)
https://warcraft.wiki.gg/wiki/API_C_...itleForQuestID - Includes Example Code
Or a combination of :
C_QuestLog.RequestLoadQuestByID(questID) and monitoring QUEST_DATA_LOAD_RESULT event for quest data access if it wasn't available before.
https://warcraft.wiki.gg/wiki/API_C_...tLoadQuestByID
https://warcraft.wiki.gg/wiki/QUEST_DATA_LOAD_RESULT
Or like I did, use the QUEST_ACCEPTED part to access the quest info at the point it becomes available to you. It all depends on how your addon is supposed to work.
I would suspect that the name of the quest would be automatically localized - similar to spell names and professions etc.