Plague Bearer Still Unmodifiable by Hit Damage Oriented Support Gems

Even after the bug fix to make Plague Bearer count as area damage (and thus affected by concentrated effect), it still cannot be modified by gems such as deadly poison or Heft.

If this is due to the "display skill deals secondary damage" description I found on PoE.db (Pretty much at the bottom), can this please be explained in the in-game skill description? With a corresponding Keyword description?

I have no idea if "secondary damage" is the same as it was in PoE 1. In PoE 1, secondary damage was modifiable with support gems, so if that's the reason why Heft doesn't work, obviously it doesn't work the same as it did in PoE 1.