Low cost way to fix keyboard not working on MacBook Pro 2016
Solution 1:
It is likely the liquid made it down to the system board and that can not only short out components but causes corrosion that can get worse over time. Corrosion can short circuit as well as cause open circuits.
The way to fix it is to dissemble the laptop, clean it and then use schematics and a microscope with very fine soldering tools to find the problem and replace chips, etc. Or you can swap the system board.
Louis Rossman is a board level repair technician who has a YouTube channel where most of the Mac's he fixes are water damaged. You can see examples of what corrosion does to a system board by watching a few of those videos. I am not suggesting that you follow these videos and fix it yourself. But Louis shares the videos for educational purposes.
I would say, just buy a bluetooth keyboard to hold you over till you can get a new Mac.