I was doing sidejobs for Delvin, as my character hasn't yet become leader of the Thieves Guild, and I notice I now get jobs involving Raven Rock. Is there now another special quest I have to complete to become leader of the Thieves Guild, or is it still just the quests in Whiterun, Solitude, Windhelm, and Markarth that I need to do to become the Guild Leader?

Same quests its just that sometimes the radiants take you to errm unexpected places randomly

there is one guy in raven rock who has connections to the guild. who that is? i'll let you figure it out