I’m building a Node.js project with an outdated Create React App.
I’m not a react developer, I’m just using what i assume, an outdated react project.
I have always encountered issues, dependency related and other types, with React.js.
And I could not find a solution for the following issues.

browser.js:49 Warning: [JSS] Could not find the referenced rule hover in ArwesSounds(Frame), Themed, Dynamic.

I’m using Arwes framework, Arwes is used in four files in the components folder.
I’m not sure what the error means.

VM55:1 Uncaught (in promise) SyntaxError: Unexpected token '<', "<!DOCTYPE "... is not valid JSON

The network response in the console is expected to return an empty array as json, instead it’s returning HTML.

And another error is

access-control-allow-origin:*

It’s expected to be

access-control-allow-origin: http://localhost:3000

This is where the issues started

Since I’m building on top of, what I assume, an outdated React project,
do I stop working on it, or could these issues be solved?