We also had this problem of not being able to utilize our “Top Engaged” contacts from marketing emails, and wanted to introduce you to Segment Builder, a HubSpot Marketplace App that solves for this.
Segment Builder allows you to create “Segments” of top engaged contacts from individual marketing emails, Campaigns, Subscription Type, or a combination.
Exactly as you describe, you can specify a percentage or a threshold, and the segment will sync HubSpot as a List, making it workable with all other parts of HubSpot.
Please do try it out for free, and I would love to hear your feedback if you have any.