I wish I had your ability to analyse and mod this stuff.
Unfortunately, SH3 and 4 had many things, like voice, that were never implemented by any patches. I doubt SH5 will see any changes.
I reviewed the cheer .ogg files for both versions and it was pretty lame indeed. One guy saying 'yay'.
Someone should have a beer party with 4 or 5 friends and record them just as a hockey goal or football score is made. That is what it would be like.
These guys have just gone through, perhaps hours of tracking and stalking a target. One guy saying 'yay' is just a little anti-climatic to me.