[Baertram]

ZO_Tracker in API 10022 is a kind of "class" for the variable QUEST_TRACKER.
You build an object QUEST_TRACKER using the methods and attributes defined in ZO_Tracker.

See file questtracker.lua:
https://github.com/esoui/esoui/blob/...esttracker.lua

function ZO_QuestTracker_OnInitialized(self)
    QUEST_TRACKER = ZO_Tracker:New(self, GetControl(self, "Container"))
    ZO_QuestTracker.tracker = QUEST_TRACKER
end

So calling QUEST_TRACKER.InitialTrackingUpdate() should do the trick.
Not sure if it's the same on PTS though.