Hi there,
After listening to your feedback, we’ve now launched a brand new formula editor for Aggregation Column Type 
Previously you could only choose pre-built aggregation functions like SUM, AVERAGE, MIN, MAX to rollup your linked rows data but now with the brand new editor, you can choose to define a formula between two functions say for example… SUM(VALUES) + AVERAGE (VALUES) to rollup exactly how you’d need it.
Let us know what you think of the possibilities of using Aggregations (Rollups) of your data and what new doors does it open up? Comment below 