Hi there,
Thanks for reaching out. I will try to help with your question. Please note that we are limited in the amount of support we can provide for customizations such as this. That being said, I will try to help if I can.
Do you have a fork of this on GitHub I could take a look at?
You should be able to add multiple linked post types if you make sure to rename all of the instances of “instructor” and “Instructor” with your new term.
You mentioned only replacing “case sensitive” mentions of “instructor,” is it possible you missed some Class names or function names somewhere because of the case?
Also, did you make sure to rename the directory name inside the view folder?
Thanks,
Sky