As per the documentation: The generic language support only stems words to themselves, queries in these languages will not include variations of words based on their meanings in the results.
xdmp:document-insert("/lang/test.xml", <el xml:lang="fr">chats</el>)
Considering I do not have a license for french language, will the word "chats" be stemmed to "chat" in the term list ? or will it be indexed as chats, i.e. without any variations ?
You can easily check this yourself using cts:stem:
cts:stem("chats", "fr")
Without necessary licenses it simply returns chats.
HTH!