Update: I found a Mac app which does what SubtitleEdit does as well. It's called Subs Factory and allows me to put in the ripped MKV file as well as the original subtitles and the downloaded ones for comparison. Re-syncing is way easier than I thought.

Hope this helps other newcomers as well!

Hi everybody, I am a brand new user and immediately VIP on OpenSubtitles since a few days. I’ve been getting my hands on the whole Blu-ray ripping and remuxing thing since then, too - which means, I'm completely new to the game. I’ve just encountered a strange problem though. I’ve ripped a French Po...