Regarding Q4, could you create a jira issue in XWiki Platform - XWiki.org JIRA for it please since I’m confirming we’re missing a translation key in SolrSearchAdmin.xml:
#elseif (!$isAjaxRequest)
{{success}}$escapetool.xml($stringtool.capitalize($request.action)) successfully triggered.{{/success}}
## Only administrators with programmings rights are allowed to execute a custom query.
Thanks