Yes it does!

All of those should be governed by Amplitude. For Alchemist, the Vials get bigger and the random buff you give out has a bigger range. Which conversely should mean the Medic shared healing should be bigger (don't have Medic leveled much, didn't test further). All of the Medic skills should fall under Amplitude as well (Wellspring did get bigger when I tested). I tested all this using the Handler dog.

Afaik the main things affected by Resonance are like Offensive Gas cloud effects, like Sporebloom.

Which when you think about it doesn't make much sense because beneficial effects like shared healing and buff sharing should be an 'aura' in most other games.

I just tested in on alchemist vial of life and it works.

It does, tested it.

Test on the dummies?

I had the same thought!

Sadly.no.

I just tried it now with the dummies in Ward 13. I performed the Spectral Blade AOE on a dummy until I was not able to hit it. Then I respec to put points into Amplitude and tried again from the same spot where I could not hit the dummy. Still no contact.

Spectral Blades is a "Aura" not a "AoE" by tag.
Same to many Skills & Mods.
There is 2 "AoE" effect suites.

It's a whittle counter intuitive though.

Spectral Blades is "weird" but might be cause it "wall phases" as well. Auras don't...obey walls unless there is a special type of wall (Very select walls protect from Aura)
While AoE "NEVER" pen walls. It's one of the "ONLY" splitting definers. It might be the "Explosive" tag is the true definer cause some weapons/mods/skills have that.

Sorrow is a oddity and has a "Explosive" tag meaning it's "return" pull out is a "Explosive" prob with a tiny blast radius. But it triggers the Explosive = Burn Damage tag for a specific amulet.

And Medic and Alchemist’s AoE skills as well.