Hi,
You don't need a live server from me because you can replicate it locally on your dev machine.
In your template distribution, here is what I did this morning to reproduce the issue:
Alongside all the html files, js and css folders, create a new "test" folder. Copy index-classic.html in the test folder.
Modify the html file so that it links to the needed files as absolute paths instead of relative paths (especially replace js/functions.js by /js/functions.js - css and images paths are not necessary to replicate the issue).
Using Visual Studio code and your live server extension of your choice (I'm using ritwickdey.LiveServer), or your own local server, start the server (from the "Canvas7 Files" folder) and navigate to https://localhost:port/test/index-classic.html.
In the Network tab of the browser debug panel, check that jquery and other plugins are not loaded correctly since it tries to load them from the test folder instead of the root.
Note that if there is an issue with js files, there may be an issue with css files when referenced as absolute paths too... But I don't know in which circumstances it could happen. I understand that your code loads plugins when needed. Do you also load CSS dynamically sometimes?