Horizon Analytics - Report Builder - Multi-Aggregated-Column Calculations

I would like to be able to do column calculations in Report Builder with aggregated data. Currently, I think this can only be done in Data Designer, which is a heavy lift.

For example, I have taken our data which is structured monthly and created a custom field in Report Builder to group by Quarter (A). However I am not able to accurately report out quarterly metrics like sum(B) / sum(C). In the data object, D is a calculated field where B / C = D, but I cannot recalculate that accurately with row-grouping, best Report Builder can do is take an average of the values in D. This is not accurate or helpful to report, and can result in D showing 50%, but the actual math of sum(B) / sum(C) = 47.5%