If I wanted to change the name of the Points Store to the Pentacles Store, would I use:  https://witches.chat/adminzone/index.php?page=admin-lang&language=on&lang=EN&language_file=on&lang_file=points

This seems like the right place to, SITE-WIDE, change Points to Pentacles. Am I on the right track?

 

Almost, pointstore.ini (you linked to points.ini).

As Composr is translatable, everything can be reworded, except for code-like stuff (e.g. URLs, some references in the raw HTML code, CSS references, etc).