I tried it using Finder, navigating to Applications, right clicking on the app to rename, moving to "information" and renaming it there.
What you have essentially done here is changed the name of the app bundle. An app bundle is a special kind of a folder in macOS that contains the app executable and the associated file. This doesn't really renames the app, just the container which is abstracted to look like the app.
This works in most places where the app name appears, but if I have the app opened in fullscreen and I swipe up with 3 fingers I still see the old app name in the menu at the top of the screen.
You can't technically rename the app name, as it's something that's wired in when the app is created by its developer. The name that you see on the top is the app's menu bar, and its not generally possible to change the name that gets displayed by the users of the app (only the developer can change it, when they build the app).