Since I don't know the structure of your files, I can't help entirely, but I would use find/locate to get a list of file paths, then use a script to take that list and use sed for the replacement, like this:
#!/bin/bash
for i in ListOfFilePaths.txt
do
sed -i "s/oldtext/newtext/g" $i
done
Please copy the entire line for oldtext and newtext to avoid accidental replacements.
Also, I am very new to scripting, and this likely has multiple problems with it. I am just throwing out ideas.
Looked at your github. I would do this in a script:
Once again, probably not the most efficient way to do it, but it might work.