Before 7.0 the cvar "trackQuestSorting" can be se to "proximity", and Blizzard will use SortQuestWatches() to sort watching quests. But it's broken now in 7.0.3. All the codes are the same except SortQuestWatches() does nothing.
I write this addon to provide a solution for this situation, by simply replacing the API GetQuestWatchInfo().
The addon updates all quests distance twice a second. if a nearer quest is found, a "click" sound will be played, and the quest will be highlighted (use API SetSuperTrackedQuestID). If you manually highlight one quest, the selection will be kept for 5 seconds, before the nearest quest is highlighted automatically.
It works fine for me these days, but if you encounter action blocking issues, you can just uncheck the checkbox on quest watch header and reload UI.
Hope all of you enjoy your Legion journey :)