I think you can only register a CustomRequestHandler on the first part of the path, i.e. nl/. You then need to parse the remaining path yourself.
Yes sure, check out the deeplink module from the appstore: https://appstore.home.mendix.com/link/app/43/
Why not use the deeplink module and set it up that a string is given as parameter for the path patterns? This way you could do pattern matching in microflow to determine to which page the user has to go.
Otherwise you would need to adapt the deeplink module so that it is not looking for /links/ but for the /nl/foobar/ part to do the deeplink handling.
You can create your own custom request handler in Java. The deeplink module can be used as an example. In that case you can handle “/nl/foo/bar”