How to change where a url points locally

Question

So I'm on ubuntu and I'm using station, a sort of web app. It grabs some of its icons from a server. However, this server is no longer maintained. Therefore some icons do not display properly and some of the UI is not very usable. So I wanted to know if there could be a way to set locally that when the URLs of that icons are "searched", my computer searches instead a file stored locally on my computer (I was able to grab the URLs so that's dealt with). My next idea would be to try to edit the source code but I'm not should I would be able to achieve that. Thanks