I bounced through a few different episodes of Dummy and had both English and Spanish audio tracks available to select.
Have you tried pressing the * button on the Roku remote while the episode is playing, selecting "Accessibility and captions", then "Audio Track", English.
Other way is to press the Pause button, then press the Up arrow button to highlight Captions and Audio Track, which will bring up the above menu.
Roku Community Streaming Expert
Just another Roku user... I am not a Roku employee.
Insignia RokuTV, Ultra 4660x, Premiere+ 3921, Express 4k+ 3941