Multicast trait and Cabalist combo

I’m playing cabalist, with part of my build being based on trait Chain Spell (when you manually cast, cast two more random spells of the same class) and use of Elemental Tome gem.
The multicast ability seems interesting as the other part of my build makes use of the On The Rocks trait (attack one additional time for every spell cast since your last attack).

The question is if Multicast would trigger in the following cases (in addition to the expected case of manual casting):

  1. On a triggered cast due to the gem enchant that doubles the cast of the spell (with x% chance)
  2. On a triggered cast due to Animated Gem (as per Cabalist Familiar perk).
  3. On a triggered cast due to Cabalist Quickdraw perk (chance to cast an ethereal gem when you receive it)
  4. On a triggered cast due to Cabalist Battle Mage perk (chance to cast an thereal gem when you attack)
  5. On a triggered cast due to the Pallida trait (chance to cast 3 non ethereal gems at start of battle)

Anybody knows how the Multicast trait interacts with these mechanics?

Multicast: “Your creatures Cast spells 1 additional time, but their spells are 30% less potent. This trait does not stack.”

Since it does not specify “manually cast”, it should add 1 cast to any cast by your creatures, even casts initiated by another effect. I’m fairly certain this does not apply to animated gem since it’s the gem that casts when it triggers instead of the creature.

So 3, 4, and 5 will all get 1 additional cast added. I don’t believe 2 will.

As for #1, multiple casts of gems are not multiplicative, if it says cast one more time, it will be just one more time. If a gem has an enchant for 100% chance to cast twice, and you also have multicast as a trait, you’ll cast that gem 3 times.