Resolution
Enable -Dfile.encoding=UTF-8 as a Java parameter on CloudBees Jenkins Operations Center (CJOC) and the client controller.Setting -Dfile.encoding=UTF-8 will require a restart of Jenkins for the Java parameter to be picked up.You will also need to set up a cluster operation on CJOC to reindex the jobs on Jenkins as documented in the "Reindexing for CloudBees Jenkins Analytics" section here.
The incorrect folder delimiter can be removed be deleting the specific build index as documented in How to delete an index on Elasticsearch.