Having a quick look at the add-ons code,
the build line is:
pip3 install \
hass-configurator=="${CONFIGURATOR_VERSION}"
Doing a quick search for that package - brings us to -
As you can see the code hasn’t changed for 3 years in that package, and indeed looking at the HTML for it -
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1.0" />
<title>HASS Configurator</title>
<link rel="stylesheet" type="text/css" href="material-icons.fallback.css">
<link href="https://cdnjs.cloudflare.com/ajax/libs/MaterialDesign-Webfont/3.4.93/css/materialdesignicons.min.css" rel="stylesheet">
<link rel="stylesheet" type="text/css" href="https://cdnjs.cloudflare.com/ajax/libs/materialize/0.100.2/css/materialize.min.css">
<link rel="stylesheet" type="text/css" href="style.css" media="screen">
<script src="https://cdnjs.cloudflare.com/ajax/libs/ace/1.9.6/ace.js" type="text/javascript" charset="utf-8"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/ace/1.9.6/ext-modelist.js" type="text/javascript" charset="utf-8"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/ace/1.9.6/ext-language_tools.js" type="text/javascript" charset="utf-8"></script>
</head>
We can see many requests for Cloudflare hosted javascripts, which of course once downloaded will be served from the browser cache without reaching out to cloudflare until the browser cache has expired, or a fore reload has been requested.
In short, nothing in the file editor codebase has changed, it has always requested resources from Cloudflare.
EDIT:
And here is a github issue in which the developer explains exactly why it’s never been updated to host everything locally.