I have many Google Custom Search engines that I need to track. In other words, I need to know the search terms of the users. Otherwise, it is hard to improve the engines. How can I do it?
If you're using Google Analytics, you could enable "Site Search":
On Step 6 it's important that you enter this exact formula into the Field A -> Extract A field:
If the results page of your Google CSE is on your site, you can just analyze your access logs to pull the search terms out. You should see URLs like