You should not edit the files in the lib folder. When you use the UI the routes are stored in app/config/routes.json. The server will read the config file and setup the routes.
The above is enough for 99% of the routes, if you need to do some special route handling or custom middleware then you can create a file in extensions/server_connect/routes, see the following doc at Extending express (NodeJS) - Docs / Wappler Extensibility - Wappler Community.