We save an EW schedule file for each of our services, with the date embedded in the filename. Is there a way to search those saved files to find out when we used specific songs?

I figured out a hack way to do this. EasyWorship stores its service files in zip format. The file contains a SQLite database with all the slide info, and additional files for any media (images, videos, ppt, etc.) in the service file. On macOS (would work on any *nix), I can unzip the service file using the "-p" option and pipe the output straight to grep. The grep output will tell me "Binary file main.db matches" if it contains the search string.

For example, to see if "Service.ewsx" contains "It Is Well" you would enter:

unzip -p Service.ewsx | grep "It Is Well"

With a simple shell script, you could scan every .ewsx file in an entire directory or set of directories to find the ones that contain your search string. It's not great, but it's much better than not being able to search at all.