facets.xml

 <terms>
      <term>
          <path>date</path>
          <facet>date</facet>
      </term>
  </terms>

facets.xquery

xquery version "3.1";

declare function local:get_facet ($books as element()*, $path as xs:string, $facet_type as xs:string ) as element()?
{
 <facet type="{$facet_type}">{  
  for $book in $books 
    let $fld := $book/*[name(.)=$path] (: Check whether name of element matches the string value of $path :)
    group by $f := $fld 
    order by $f descending
    return element {$facet_type} {attribute v {$f}, attribute number {fn:count($book)} }
  }</facet>
   
};
let $corpus := fn:collection("fleurs-du-mal")
let $facets := fn:doc("https://gist.githubusercontent.com/AdamSteffanick/ab59d4c20590cfc0213c/raw/68b09633bef948c460d5ed0e36976bdf7ffd0677/facets.xml")

(: return $corpus//*:imprint/*:date/text() :)
for $facet in $facets/terms/term
return local:get_facet($corpus//*:imprint, $facet/path/text(), $facet/facet/text() )