Administrators is a special role in Sitefinity and for users that belong to this role the permission check is "skipped". Inside the web.config there is a section <security> where you can try to add your role and set permission attribute to Unrestricted.
<security defaultProvider="DefaultSecurityProvider" cmsProvidersName="Sitefinity">
<add name="Administrators" permission="Unrestricted" />
<add name="CustomRole" permission="Unrestricted" />
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