Custom CSL did not pass CSL 1.0 validation

Working on Drupal 7.67 with the last Bibliography version.
I need to import a custom CSL style (Chicago style slightly modified, attached to this post) provided by my client but it did not pass CSL 1.0 validation.
Looking at the code and through Visual CSL Editor (https://editor.citationstyles.org/visualEditor/) no error message is displayed.
Do you know what must be modified in the .csl file so I may use it in Biblio module?

EDIT: here is the error message I got in the log :

Warning : DOMDocument::relaxNGValidate(): Expecting element locale, got style dans biblio_citeproc_validate_csl() (ligne 726 dans /home/mywebsite/public_html/sites/all/modules/biblio/modules/CiteProc/biblio_citeproc.admin.inc).