Hi Matthew Y.
Thank you for reaching out Microsoft Community. Congratulations!
We're sorry to know that the Surface device was spilled with water. Well, I wouldn't be able to confirm if that's the only problem you'll be experiencing through time with the keyboard of your Surface Book but there will be possibilities that the keyboard keys will no longer work anymore. I can say this because it happened to one of my devices that was spilled with water and I thought it was just okay because it was still functioning up until I can no longer see anything on the screen and some of the buttons don't work anymore. In the event that the device stops working, the best resolution we can provide is to process a replacement for that unit if you'll prefer to get it replaced.
As of the moment, please follow the troubleshooting steps below for us to see if the keyboard issues you're experiencing now can still be fixed.
Open Device Manager
Expand Keyboard
Right-click on keyboard drivers available and select "uninstall device". If there's another dialog that will show up before you can uninstall those drivers, please leave the box unchecked and just proceed uninstalling the keyboard drivers.
If it doesn't fix the current keyboard issue, then this is the after-effect of the water spill and it's considered as a hardware problem already.
If this answers your question, feel free to mark this post as an answer. Otherwise, don't hesitate to respond to this thread if you need further assistance.
Kind Regards,
Crest_Z