More customization options for the goal metric

For outbound messages / series, I’m able to select a goal metric to help measure the effectiveness of the content. We typically use product events as those goal metrics to track how well a post influences a user to take a specific action. 

Some of our product events have subcategories (parameters) like, filter added » filter A vs filter added » filter B, etc. Those subcategories aren’t accessible as goal metrics. 

Currently, rules nodes can specify a subcategory of an event, while goal metrics cannot. I’d love to see parity between these two options. Thanks!