How to change a Webflow interaction keyframe's value with JS/Jquery?

I’m making a page with a horizontal scrolling section in it (I’ll not bother explaining how this works as the video does it better than I can).

The content in this section is a CMS list. So there is an unknown amount of content. The challenge is I need to set both the “track” height and it’s interaction’s last keyframe based on how many items there are.

It’s easy to set the “track” height using a few lines of Jquery like so:

var count = $(".frame .item").length;
$(".track").css("height", `${count * 33.3}vw`)

But how do I change how much the last keyframe moves the “frame” with a script?