I'm creating a Dataplane report which has Status and Severity. I want to change the Severity names.

[RD]

I'm creating a Dataplane report which has Status and Severity in a pivot table look.  I need to change the Severity column titles from "Severity 1" to "Critical" (as one example).   I've tried the groovy script (customizer script) and do not get the results.  

customizeChart {
seriesRegex ("Severity 1", "Any") name "Critical"
}