I was told that skills minions use work so long that it does not say “You” as it’s then you who cast it.
But I just tried making a Shaman with a Bear that cast Earthquake and then took the node where EQ can spawn Boulders from Avalanche.
But that does not work, no bolders, have I missed something, or is it a bug?
Mind posting a link to your build in the planner? My initial suspicion is that you might have Seismic Smash and that’s the issue, but if you post your build I can do some testing on my side, see if it’s an issue with the build or a bug or what.
Ofc 
https://www.lastepochtools.com/planner/ALJ59adB
One other thing i do not have the Mountain Peak node on Avalanche. that was just testing.
It seems like it should be cast by the bear. So it’s either a bug and it should work or they don’t want it to work and it’s instead an outdated description (which can also be seen as a bug). I would first ask the devs on discord, just to make sure, since they tend to answer this fast, then submit a bug report.