1. I'm a developer, so I am familiar enough with SQL and its errors to try to figure out what's going on.
2. Basically, whenever the ClientKeyData table is updated (when a client registers with a new certificate in our case) the trigger takes some of the updated data and throws it into the "TableChangeNotifications" table. Not doing this insert probably breaks some sort of post-processing routine somewhere, but I haven't noticed any issues since I disabled the trigger yesterday. The trigger didn't exist in 2012 R2 without SP. In our environment, the potential risk of this missing post-processing is lower than a complete breakage of our build procedure, especially coming up to summer break when we'll be building and rebuilding hundreds of machines.