.rpy is the text version that is readable for humans.
.rpyc is the compiled version that is readable for computers.
The extra pack included the .rpy
Launching the game would create an .rpyc from the .rpy
The extra pack also included screens.rpy.org
I have no knowledge about what that is, but opening it in notepad it looks identical to the corresponding .rpy
But, as mentioned, that doesn't seem to be the only issue.
And as
SonsOfLiberty says/suggests (I'm not 100% sure how to read what they wrote) the extra pack was (probably?) for the old version, not for use with the remaster.