Yeah that's already broken really, because the National Rail website lets you specify 120 minutes, but for the journey I chose (Chester to Hawarden Bridge changing at Shotton) it defaulted to Transport for Wales as the operator.
When I clicked the button to buy tickets, it took me to the TfW website with a blank search form, effectively starting me from scratch. The TfW website allows 5, 10, 15, 20, 30, 45, 60, not 120 (though you can fudge that one by changing `interchange_adjustment_time` in the POST request body

)