Seeking Reporting Framework Suggestions

We have built a reporting framework that allows customers to customize columns and filters to generate a custom report. The customer is asking for more flexible filtering, including defining operators between filters and grouping filters, basically a UI for building logical expressions. Furthermore, the customer has more complex reporting requirements such as generating reports with dynamic columns, based on selected filters.

We have a potential solution for the flexible filtering requirement, but we have performance concerns as our current filter framework uses nested CDTs

Are there any existing solutions or examples of report builders / query builders in Appian? Also, what is Appian's recommendation for handling complex reporting / data analysis? 

Thank You