In some cases in the XSLT we have a translate function on the link text instead of the link itself (where it's supposed to be used). These cause that () in the text are not displayed and should be removed.
I just ran into this again, we need to make this change in the Utils files for OPAC and staff interface: <xsl:choose> <xsl:when test="$UseControlNumber = '1' and marc:subfield[@code='w']"> <a><xsl:attribute name="href">/cgi-bin/koha/catalogue/search.pl?q=Control-number:<xsl:call-template name="extractControlNumber"><xsl:with-param name="subfieldW" select="marc:subfield[@code='w']"/></xsl:call-template></xsl:attribute> - <xsl:value-of select="translate($f773, '()', '')"/> + <xsl:value-of select="$f773"/> </a> </xsl:when> <xsl:when test="marc:subfield[@code='0']">