So, for guidelines, I started out by following the BBC guidelines (which are similar), but adjusted them to have a strong emphasis on readability for younger viewers. This means that, when given a choice, my subtitles opt to show lots of text for a longer duration instead of several briefer displays of short text.
Basically, if you’re making a new translation and want to stay within the project’s style recommendations, just use the project’s template files and that will take care of almost everything about timing, grouping, etc. The README covers a few other style issues. (existing Swedish subtitles do not entirely follow these guidelines because they’re pretty much straight from the GOUT DVD with only minor modifications)
I’m not replying just to you but Rondan and other possible translators as well.
It would be easy to use English guidelines for all languages but unfortunately all languages don’t have the same readability. I can easily read English subs with fast speed but reading the subs on my own Finnish language at the same speed literally gave me a headache. That’s why every single sub from my translation has its own timing that I manually made. I don’t remember anymore if CatBus changed the timings from what I originally sent, hopefully not. 😃 So Rondan, if you’d start the subs from scratch (which I recommend) I’d use the English subs for the basis of the translation, look for help from the GOUT subs and then time them all from scratch. On mine I used at least 100 milliseconds of free time between the subs so that the text wouldn’t look like it would change but the whole subtitle. Other than that I tried to maximize their readability time. That way you can get the most quality out of them.
Edit: oh, and if you want, you can use the Finnish subs for help in timings. Of course you’d need the English subs to understand the dialogue, but I’m pretty happy about the durations. Swedish maybe could be a little faster as the words are shorter, I don’t know.