Project is on the backburner, but there are some good news - I found a way to extract scripts from voiced JP version - AE was able to extract files, and then isfcodec to decode. After that, ArcTool can extract strings using the same method as with translated version.
So now it should be possible to restore that missing line from Matsuri's route, and also, when I finally get to it, I should be able to compare TL with original text, which may come useful when fixing those few lines that are hard to understand in TL.