Please don't include information about either the Twine Compiler or the Story Format you are using within the Question Title, it just makes that title longer that necessary and serves no real purpose if you have used the Question Tags to state this information, as you have done.
(although knowing the full story format version can help as that can effect answers).
Based on the fact you stated "I want to allow allow interested players to create custom versions of some of my encounters" I am going to assume that your game is not going to be hosted on a web-server.
Unfortunately web-browser's are very restrictive (for security purposes) when it comes to accessing locally stored files, excluding the standard file types that a HTML file normally references. There are a number of techniques you can use to try and get around these restrictions but none of them work for all web-browsers.
This GitHub Gist page lists two of them along with links to further information about those techniques.