When the result is "A warning has occurred while searching: Sort order of last_edit_desc is unrecognized, default sorting will be applied. Valid sort orders are: relevance", does this imply something additional must be configured or added at the MediaWiki API level for date-order searches to be enabled? MediaWiki 1.34 is installed with CirrusSearch, AdvancedSearch, Elastica and ElasticSearch all otherwise apparently happy, and recognized under Version. I'm so far unable to find documentation on what the missing piece might be.
Topic on Help talk:CirrusSearch
If only "relevance" is shown I suspect that CirrusSearch is not properly activated did you set $wgSearchType = 'CirrusSearch'; to activate CirrusSearch?
Thanks. I'd indeed managed to miss that. The web page on installation is partly redundant with the README about setting up CirrusSearch, so on seeing the redundancy, I managed to overlook that only the README mentions adding the $wgSearchType line. Since the requirement for that appears to be a constant across CirrusSearch generations, it might be logical to put it in the web version of the instructions, along with the other LocalSettings requirements which are listed (redundantly) there.