Summarizing detective work by Alterworld here, there is compelling evidence that the architect is Arnaud Lacours (from Waking Titan.)
And a quick recap of June 17 if it’s helpful: it appears that the Tower is the secondary site. Vector_cmdr did a deep dive into that site, and a security log promptly appeared on the skyscraper site saying that the Tower security had been compromised and the opening_door_protocol was terminated. Ghost sent Architect an email saying that Ghost needs access, and System sent vector_cmdr an email saying that System needs the connection. Operators sent in messages to System offering to help; no response until June 18 when vector_cmdr was able to reestablish connection via System (which alarmed the architect.)