Why are certain talent stacks associated with upgrade events?

My quest to find quest progress data continues, I ended up finding Nova's snipe master stacks in NNet.Replay.Tracker.SUpgradeEvent but not any other talent. So I started looking at the game data to see if there's any reason why this may be.

Nova is one of a few (I think only Gall has a similar statement) heroes that has a `` tag, causing the data to be carried over to the replay SUpgradeEvent packet. Other talent/trait quests use Tokens as defined in Galaxy scripts via `UnitSetTokenCount` and `UnitCreateEffectUnit`, which are seemingly missing from replay data. Why don't all quests use CUpgrade, or how/why isn't token data in the replay?

Chromie has "ChromieSandBlastPastAndFutureMeQuestToken" and "ChromieSandBlastQuestToken", neither of those strings are present in the replay.