Have you even tried to take a look into DBCs? I'd say nope, because I found what is most likely wrong in like 5 seconds .EmotesTextSound.dbc. I'd say its emote ID, race ID, gender, sound entry you need to enter there for every single race/gender combination and for every single race you have retro-ported.SoundEntries.dbc. Create sound entries for your emote sounds.And finally, get your hends on original emote sound files and reffer them from SoundEntries.dbc.
Same thing happens in classic, i guess in all models that are rertoported to any other expansion from WoD and bellow. Its the specific emotes the doesn't work, like i.e. laugh or cry etc. But yet since you dont change any files and use same things really cant understand too why those specific files aren't working. And as filsternis said you dont actually hurt anything during editing in blender, other thought is something might go with the converter/s.