Add a string, not replace it

Is

part of a record or only the name of a worksheet?

In general, there is a section in the FAQs how to add a string to a field

If "enregy-03" is part of the record, do not import it to the target field directly but to a user-defined field first, e.g. %energy-comment%
Then use an action of the type "Format value" for comment with
Format string: %comment% %energy-comment%
Afterwards you may delete the field %energy-comment%