Frost Wall and Cast on Crit mechanics

Haven't seen any mention of the fact that critting Frost Wall ice crystals generates energy for Cast on Crit (But not CoFreeze or CoShock that I could tell), which seems like a really potent combo. Just a jumble of observations from playing around with the two:

It scales with the number of crystals hit. Plain Frost Wall is 6 crystals, Fortress support takes it up to 12, Spell Cascade can triple it for up to 36. Spell Echo doesn't seem to help, the second wave of crystals just seem to replace the first.

Frost bomb was gaining about 5.5 energy base per crystal crit for me, so it was pretty easy to generate hundreds of energy per cast of Frost Wall, even though I didn't have any investment into it on my character.

The crystals can count as being on full life for Ambush support, making it relatively easy to guarantee crits.

The energy gained scales directly with damage. Comet generates nearly double the energy of a Frost Bomb. A 25% more damage support generates 25% more energy. This seems broadly pretty important for Cast on Crit builds in general.

Overkill damage counts.

Ice Crystal life doesn't matter, slotting Glacier or Icicle supports didn't change energy generation.

Area level matters. A setup that only generated 1 proc in a level 51 Cruel Act 3 zone generated 8 procs and fully emptied my mana bar when I took it to a level 2 zone in Act 1. This also seems like a major point for CoC setups.

As a final minor note, monsters seem to have a 4 second window of immunity to chill effects from the same skill source when the chill on them expires. Ie. Frostbolt's chilled ground will chill an enemy for 2 seconds, then the monster will be immune to the chilled ground for 4 seconds, even from other Frostbolt casts. It seems like it'd make any investment into chill effects pretty useless.

Edit: Also, spells cast by CoC can't generate energy from their own crits, so you can't make an infinite loop out of it that way.