Kevin,
As we discussed in the support case, I was able to get it working, but there was a requirement of including a customization into the kt_document_template.htmpl as well, like:
In the kt_document_template.htmpl there is a line:
var arrDocument = sDocument.split("{TAG_z_fcr}");
sDocument =
arrDocument.join(highlightSearchTerms("$args.KEEP.ebr_parsed_search_text",
'<PDM_FMT ESC_STYLE=C>$args.z_fcr.sym</PDM_FMT>'));