Subtitle offset for offline items

Hi, this is just a small detail that I think could improve user experience for people who often download movies or series to watch offline.
Sometimes there’s a show that has no embedded subtitles, so if I want to watch it somewhere without internet connection, I have to prepare external subs beforehand, and then when I download it comes with those, which is cool. But sometimes it’s not properly synchronized, and there’s no possibility to change the offset when offline.
I’m not asking for an auto-sync like when we play the file locally, just a simple offset modifier to fix a small mismatch when it’s needed.
Thanks!