Well, yes, exactly like that!
Some ideas from my side:
IMHO, adding another button should be avoided if at all possible. That leave as with 1 button that would fire up subtitle settings. To reduce number of clicks, download should be at 1st (default focus) position. That is just 1 additional click and other features will more than compensate this "problem". If we put SUBS OFF as last item we could benefit from list wrapping - press up to go to last item.
OSDSubtitleSettings dialog could look like this:
- Download
- Browse
- Delay
- local sub 1
- local sub 2
...
- Turn Off Subs
If we would have ability to define preferred languages for audio and subtitles in XBMC settings, this would greatly reduce necessity to use OSDSubtitleSettings. Those user preferences could be made available to subtitle downloader add-on, so it would not be necessary to have them in add-on settings any more. I can't really comment on idea of splitting services and search functionality but it sounds to me it could be a bit confusing to download and install services as separate add ons. I use 4 of them to make sure Serbian or Czech subtitles are found (with fallback to English ones).
If above suggestions would be implemented, my use case would be:
Kids profile - 1st preferred audio track set to Serbian, second Czech. Preferred subtitles - OFF
Adults - Audio: English/Serbian/Czech Subs: Serbian/Czech/English
Hope this helps a bit.