How are the product HTML pages generated?

[DrByte]

I commented out the code on line 72 because I don't have a custom english.php file. Now only the parse error shows.

That is the *wrong* thing to do. Line 72 is important. It is not your problem; it is only "the messenger".
You'll need to undo that commenting.

The error message is telling you that it's looking for the MAIN english.php file, not a "custom" one.

First thing I'd do right now is go back and check all your files to make sure all the original files ARE actually present on your server. Anything you deleted should be put back. Anything that failed to upload correctly needs to be fixed.
Then I'd also check all your files to undo anything you changed while "troubleshooting". Making guesses at changing any original core files has probably taken you in the wrong direction.
Then look at all the files you've added (whether yourself or via a plugin) and determine what errors you've made in those files.