According to this post
how to display chinese closed captions - Roku Community
it seems like changing fonts for closed caption could be possible if the font is included in the channel. I've included the ttf file and used it to change interface fonts but couldn't figure out how to change closed caption fonts.
It feels like it should be done with the CaptionStyle attribute of the Video object but I'm not sure how to achieve it since "Text/Font" entry doesn't seem to accept arbitrary Font objects. Any help would be appreciated!
have you tried according to
https://community.roku.com/t5/Roku-Developer-Program/CaptionStyle/m-p/499570#p595085
m.videoplayer = m.top.findNode("video")
m.videoplayer.captionStyle["Background color"] = "Yellow"
Yes and this changes the background color of the subtitles. However, I wish to change the actual font to something like Arial for instance
Sorry, the Roku captions engine does not currently support using fonts other than the ones provided by the system. You should contact Partner Success about your request.