To clarify the point you're trying to make here, I think you're saying that if you cast two Sticky Bombs with Echo Shard, the second one's damage is based on the number of hit stacks you have on the spell
at the time of cast, rather than when it blows up? So both bombs you send will do the same amount of damage, rather than increasing if the first one hits an enemy.
I've made a video demonstrating.