Based on the consensus reached in https://ca.wikibooks.org/wiki/Viquillibres:La_taverna#Editor%20d'interfície, please implement the user group with the following settings:
$wgGroupPermissions['editinterface']['editinterface'] = true; $wgGroupPermissions['editinterface']['editusercss'] = true; $wgGroupPermissions['editinterface']['edituserjs'] = true;
Thank you, --[[:ca:User:Gerardduenas]]