So this is a faction issue and perhaps it can't be adjusted using the current Live values but I think I have seen other posts saying that factions haven't changed all that much so thought I would give it a shot.
First of all here is a link to the the quest on alla in the wayback machine:
Heretic Battle
And here is the current quest:
Current Heretic Battle Link
So here is the situation, I killed
Elial Brook 45 times and got 45 bones. I killed this guy
Aglthin Dasmore around 15-20 times as well.
This killing by itself only got me up to threatiningly faction with the caster guilds (still ready to attack with the pally/clerics). I then proceeded to turn in the 42 bones I collected using sneak to the Heretic Battle turn in guy (the first attempt I did 4 at once and only got one faction hit). After turning in all of those I only got moved up from threatiningly to apprehensive.
2100 should be enough to shoot me way past apprehensive even if I was on the low end of threatiningly. Also during the process I got to the worst possible faction with the heretics (I was just under dubious before I started the bone turn ins because I had been watching my faction on each kill). This also shouldn't be possible with so few turn ins if the -7 is accurate.
I also think that the faction hits for Elial and Aglthin may be off because I killed them so many times and still couldn't break out of threatiningly. I checked faction multiple times during my kill sessions of Elial and Aglthin and was sitting at threatiningly for longer than I would expect given the high faction hits listed for those two.
Anyhow sorry for the long post and if nothing can be done I guess that isn't the end of the world but seems like these are just wildly off.