I've only encountered Waylens-induced warning lights a few times with my 2014 BRZ (hey, Subaru club in this thread!), but when it did occur the car was placed in a limp mode as well with limited throttle response until I was able to clear the codes. While the trouble codes may indeed be false, the car's reaction to them is very real - and particularly annoying since most of those problems where encountered while in an autocross grid area.
For what it's worth, I actually saw the same problem much more regularly before I started using the Waylens. That was with a variety of datalogging apps (Harry's Lap Timer, Track Addict, Torque) connected to the car via an OBDLink LX adapter, and seemed to occur in scenarios where I had left the logging running when I turned off the car and started it back up again a few minutes later. Pulling the code revealed it to be U0073, which points to a control module communication fault - and it's apparently a not-infrequent issue. I guess the car gets grumpy if an ODB adapter is trying to talk to it before it's good and awake. The problem went away entirely once I got in the habit of shutting off the datalogging apps prior to killing the engine.
The infrequent Waylens issues seemed to follow a similar pattern. I never turn off the camera manually (instead letting it time out automatically after ten seconds), but the warning lights might appear if I started the car again very shortly after turning it off. Again, I now make sure that the camera is completely powered off before I start the car up and I haven't encountered it again.
(I did experience the same fault when I started driving without realizing that the OBD firmware was being updated, but it sounds like that's kind of expected.)
I don't know if this jives with what anyone else has experienced, but figured I'd mention it since it seemed to be a topic of discussion here.