Thanks again for the kind words and the feedback, I'm glad you enjoyed it!
Regarding the spark collector, I double checked, and it is working, although its effect might not be super clear. The way it works is that if the enemy runs into your Echo and dies as a result, the sparks it would've dropped will go directly into your inventory. To be honest, the main reason why it's an upgrade at all is so people will read the description and go "wait, my echo can kill things?", haha.