Well, my luck is still mixed. I was able to remove the voices from just the one faction, but the game becomes rather unstable, with the same problems I mentioned above. Large battles cause slowdown or "fatal graphics error" crashes, and one unit in particular fires off a greek fire attack that launches fine, but as soon as it hits an enemy there is a crash. It doesn't happen when I don't mess around with any of the files.
I attached images of my folder directories below; maybe there is something wrong there. Here is the (probably incorrect) process by which I removed the voices.
1) I placed the 39 sound text files into the seasons\data folder (I also tried placing them into the vanilla data folder when that failed, then tried both at once). I then edited the following files according to Aikanár's tutorial:
descr_sounds_accents.txt
descr_sounds_units_confirm.txt
export_descr_sound_prebattle.txt
export_descr_sounds_soldier_voice.txt
export_descr_sounds_stratmap_voice.txt
export_descr_sounds_units_battle_events.txt
export_descr_sounds_units_voice.txt
I uploaded those as well. but I don't believe I messed up anything regarding those files. I added the "Valkyrie" accent to the first two, then copied the French accent and renamed it to "Valkyrie" for the last five sound text files. The mod uses the vanilla Voice.dat files (Voice1.dat, Voice2.dat, and Voice3.dat) from Medieval II\data\sounds, so there are no Voice.dat files in the seasons\data\sounds folder.
Were these Voice.dat files supposed to be created in the seasons\data\sounds folder after placing the sound text files in the seasons data folder and running the seasons mod? I extracted the voice files from the vanilla Voice.dat files and placed those in the seasons\data\sounds\voices folder (check image for directory). I then deleted (actually moved, I never delete files) the vanilla Voice1.dat, Voice2.dat, and Voice3.dat, along with the corresponding .idx files (the French accent would not go away otherwise), then ran the seasons mod, which recreated the Voice.dat files in the vanilla sounds folder (which were all strangely 1KB in size again). I went into the seasons\data\sounds\...\battle_map folder and moved all of the French sound files out of the way into another folder. This removed the voices from the faction (Byzantine faction is the faction I'm trying to remove the French accent from).
I'm sure I butchered some stuff in there. The adjustments work somewhat, but those issues I mentioned above are driving me nuts. I can manage the large battles, since battles need to be pretty big to cause a crash (is it just me or does unpacking the game in general decrease performance?). But I need the problematic unit to survive against other factions.
The unit in question...How can a muddy, blood-spattered, innocent face like that be causing me so much trouble?
At any rate, thanks again. I feel I may just have to conquer the world with manly French females, or play on mute.
Edit: I should mention I also tried going through the above listed sound texts and removing the the French.wav file entries from each of them. I think the problem comes back to why the Voice.dat files are not being recreated properly.