Hi again,
I tried your suggestions but I got stuck in the override registration process, since there is no ps_override table in the DB (I'm working on PS 1.7.8.x but as far as I know also PS 8.x does not have such a DB table) and to my knowledge the override process does not need any insert in the DB because override infos are discovered by PS during the installation of the module using paths in the override folder of the module itself (docs here: https://devdocs.prestashop-project.org/1.7/modules/concepts/overrides/).
Trying to override ps_facetedsearch/src/Adapter/MySQL.php using mymodule/override/ps_facetedsearch/src/Adapter/MySQL.php does not work.
Maybe I'm missing something obvious here: any more suggestions?
Thanks,
Federica