Wildcard searches might not return any results when the input word was split into several tokens during indexing, for this reason, in https://github.com/xwiki/xwiki-platform/blob/117f79533eb0a1462b1957fa5c37f1f30d1c912d/xwiki-platform-core/xwiki-platform-search/xwiki-platform-search-solr/xwiki-platform-search-solr-rest/src/main/java/org/xwiki/search/solr/internal/rest/SolrKeywordSearchSource.java#L203-L208, where I've implemented something similar for the page suggestions, I've added code for extracting the last term of the user input before adding the wildcard.
