From one of our users:
It seems that latex2edx cannot handle any package name other than edXpsl. I modified this package and renamed it, but I was unable to use the renamed package. Even when I copied the original package and simply renamed it, I was unable to use the renamed package that was identical to edXpsl. It may be convenient to allow users to use a package name that differs from edXpsl. Note that pdflatex worked fine regardless of the package name, but latex2edx did not.