Thank you for your replies
the two occasions where this happens are different.
One is infact an FMV, here's the link where you can see right at the end the section I'm talking about https://www.youtube.com/watch?v=3DYBx3ZlVMs
, as you can see the game usually does use TIMs to store its text, which we have cracked, but then the game goes from in-game to FMV and since it's a "true ending", having the final bits untranslated would be a bummer.
The other time this occurs is during a mission ("Archnemesis" for those interested) where there's about a minute of dialogue, which is important to the plot of that path. This happens during gameplay, which usually has subtitles for spoken dialogue/chatter but not here, for plot-related reasons. One good thing that might help soft-sub this section is that the dialogue has fixed timing, the player doesn't matter and the real mission doesnt even start until the characters are done speaking so it's not random at all, which should help with the starting point and timing of soft-subs.
Sadly it isn't possible to recap what is said here because by this point (end-game) TIM text usage is very sparse, and the space is limited as it is. It's either soft-subs or a separate text file for this part.