There a way to search and replace on paragraph style. But on character style? It would be verrrry practical :)
I'm talking from Scribus-NG 1.5.4.
Thx!
I'm not sure if this helps your case.
For search and replace patterns in the *.sla code (which is xml) I am using XML Copy editor ...
http://xml-copy-editor.sourceforge.net
You can wrap or unwrap the displayed code (including character style elements).
Of course other XML compatible editors do the same job.