Solr not searching titles and contents in the language of my origin copied and pasted from MS Office

Please kindly help or advise on the error that Solr is searching only attachment names (not titles, locations, and contents) on a branch in XWiki Enterprise 8.4, although it is searching everything on the main Home of the same system.

This happens even after re-importing the Solr Search UI in version 8.4 from https://extensions.xwiki.org/xwiki/rest/repository/extensions/org.xwiki.platform%3Axwiki-platform-search-solr-ui/versions/8.4/file?rid=maven-xwiki

Due to our limited resources, I have been delaying to upgrade, but I will upgrade soon.