Do we have a chance to change the alphabetical order in category pages? The Turkish alphabet has "Ç" as its fourth letter; i.e, it comes after "C".
To answer to your question : yes, it could be possible :)
Per https://meta.wikimedia.org/wiki/Requesting_wiki_configuration_changes, as it's a config change request, can you start a discussion on your local village pump about this ? Thanks !
No, otherwise they would be listed here. Please provide a configuration change patch by following https://www.mediawiki.org/wiki/Gerrit/Tutorial . You need to add one line to the "wgCategoryCollation" section in wmf-config/InitialiseSettings.php in the repository project called operations/mediawiki-config/.