Send it to the CTO, the receptionist, or even HR. hell, CC them all with a note saying that it is unknown where to send it to so hoping someone will know where to forward it. It also sounds like your company needs better internal communication about communications within the company.
Google is so huge that it's extremely common to know you have an important bug for another team, but not to be able to route it to them because you can't find their team name.
Most teams have "code names" that have nothing to do with the public name of the project. For example, the parental controls team might be named "pigglewiggle-team" and the Android contacts team might be named "katniss-team" and their bug components might have similarly obscure code names. If you don't work with those teams frequently it can be really daunting to find.
Even when the bug components have hints that get you close to the right place, it's not unusual to learn that most of the engineers are busy working on the new version of the app that isn't released yet, and the old version of the app (the one with the bug) has been destaffed and bugs are supposed to be routed to some other random team that's literally never touched the code.
This giving codenames to projects thing seemed so endearing when I was working in a team and company of 10, but now that I’m working in a team of 100, and an org of 2000, it’s so extremely aggravating.
Any large bureaucracy seems to do that. Either you have a relatively flat org chart, but then teams have limited visibility past their "neighbors". Or you have a deeply nested hierarchy, where there's a clear path to route requests to any given place, but it takes ages because of all the red tape involved in escalating it sufficiently to route it properly (and then people try to avoid that hassle).
Try contacting the CTO in a company of 100k+ people. Your email probably goes to their junk folder. I worked in a similarly sized company and I didn't even know the name of the CTO, nor if there even was one.
