Here's how Largo makes widget title's links and applies these fields to all widgets regardless of origin (largo, wp, 3rd party plugin, etc):
https://github.com/INN/Largo/blob/f4ddf0b27b5fc34fb826e7ac22a9c393b4cbed1a/inc/widgets.php#L211-L223

Here's where link-roundups passes the title arg (native) and title_link (largo) with filter:
https://github.com/INN/link-roundups/blob/master/inc/saved-links/widget.php#L17