Всё получается... Информацию в XSL-шаблоне изменил (дописал):
<!-- Шаблон для фильтра по дополнительным свойствам -->
<xsl:template match="property" mode="propertyList">
...
<xsl:variable name="filteringNode" select="/shop/*[name()=$nodename]" />
<xsl:template match="list/list_item">
<xsl:variable name="list_item_id" select="@id"/>
<xsl:variable name="propertyNode" select="/shop/shop_item_properties//property" />
<xsl:variable name="filterCount" select="$propertyNode/filter_counts/count[@id = $list_item_id]" />
<!-- Отображаем флажки -->
<xsl:if test="../../filter = 4">
<xsl:variable name="nodename">property_<xsl:value-of select="../../@id" /></xsl:variable>
<div class="form-check">
<input class="form-check-input" id="id_property_{../../@id}_{@id}" type="checkbox" value="{@id}" name="property_{../../@id}" data-property="{../../tag_name}" data-value="{value}">
<xsl:if test="/shop/*[name()=$nodename] = @id"><xsl:attribute name="checked">checked</xsl:attribute></xsl:if>
<xsl:if test="not($filterCount)"><xsl:attribute name="disabled">disabled</xsl:attribute></xsl:if>
</input>
<label class="form-check-label d-flex" for="id_property_{../../@id}_{@id}">
<xsl:value-of disable-output-escaping="yes" select="value" />
<div class="ms-auto">
<xsl:if test="$filterCount/node()"><xsl:text>( </xsl:text><xsl:value-of select="$filterCount" /><xsl:text> )</xsl:text></xsl:if>
</div>
</label>
</div>
</xsl:if>
<!-- Отображаем список -->
<xsl:if test="../../filter = 7">
<xsl:variable name="nodename">property_<xsl:value-of select="../../@id" /></xsl:variable>
<option value="{@id}" data-property="{../../tag_name}" data-value="{value}">
<xsl:if test="/shop/*[name()=$nodename]/node() and /shop/*[name()=$nodename] = @id"><xsl:attribute name="selected">selected</xsl:attribute></xsl:if>
<xsl:if test="not($filterCount)"><xsl:attribute name="disabled">disabled</xsl:attribute></xsl:if>
<xsl:value-of disable-output-escaping="yes" select="value" />
<xsl:if test="$filterCount/node()"><xsl:text> ( </xsl:text><xsl:value-of select="$filterCount" /><xsl:text> )</xsl:text></xsl:if>
</option>
</xsl:if>