I have Infuse on iOS, IPadOS and Apple TV. As far as I can see, there is no option with the latter to set automatic downloads of subtitles? Why not?
I’m here in New Zealand and find it common for Open Subtitles to be down at the time I need it. I’m assuming this is due to updates being applied to the site based on a North American time zone schedule?
But as I type this, the Infuse site is telling me that Open Subtitles is operational…and Open Subtitles is telling me that it isn’t. This could be resolved if the Apple TV version downloaded subtitles in advance.
I don’t know the official answer to your question on ATV but don’t forget, Infuse doesn’t use the web interface for opensubtitles, it uses an API to retrieve data so the website can be down and the API can still function. The same applies to the tv and movie metadata.