When adjusting reports in the text-mode, there is no feedback or even any error messages when a report is written wrong. Historically I've had to brute force trial and error until I've gotten a particular report to work.
It's bad enough that the documentation for text-mode reporting columns to be sketchy, but worse yet if there is an error the column just goes blank in the report.
We've talked to workfront directly and they've said that they will not add this as it is not "on their roadmap", but better support for simple formulas in the reports seems like an important feature.