I think the userrights were incorrectly set. In the 'ceo' user group it should be:
'+wgGroupPermissions' => array( '+igrovyesistemywiki' => array(
'ceo' => array( 'ceo' => true, 'bureaucrat' => true, 'sysmag' => true, 'trusted' => true, 'autochecked users' => true, 'editors' => true, ),
(end of fragment)
These userrights cannot be managed via Special:ManageWikiPermissions, so I decided to create this task. The rest rights I'll set directly.