The short answer is that in a repeater, you need to use the at() function to be able to assign a value to a particular item in a repeater.
https://www.wix.com/corvid/reference/$w/at
Take a look at the section entitled Repeated Item Scope in the repeater introduction.
https://www.wix.com/corvid/reference/$w/repeater/introduction
Since you are running a query, it’s typical to assign the result to the data property of the repeater. I don’t see where you’re doing that.
https://www.wix.com/corvid/reference/$w/repeater/data
I would also spend some time on what the onItemReady and forEachItem functions’ purpose and common use is. What you’re trying to do is probably better handled by these repeater functions designed to deal with populating repeater items rather than a standard javascript forEach loop. I say that not understanding exactly what you’re attempting to do …