This has been added at runtime, yes, but it does not appear to be available while doing validation currently. I will make a git issue for this.
You should be able to get the template name via
var excelReportTemplate = com.infiniteautomation.mango.excelreports.dao.ExcelReportTemplateDao.instance.get(report.getReportTemplateId);
print( excelReportTemplate.getName() );
print( report.getFilename() );
I will perhaps also create git issue for putting the Excel Report Template into context, instead of only the run report. But,
report.getTimeSeries() will get the periods the report was actually run over, as opposed to getting something like a relative definition as the template would have. Thanks for bringing this to our attention.