Well we only have Afzal, Nakhla, Al-Waha and AlFakher available here in SA but you'll only find AlFakher and Al-Waha tobacco in my stash.
I wish I could point out the particular brand or flavour of tobacco that could be the culprit but the truth is my fiance' has tried just about all the flavours I've brought home with the same end result. I do however remember that I once bought some Nakhla cherry flavoured tobacco which she was actually able to smoke and she said it wasn't harsh for her. Coincidence maybe?
Heat management? Well I only use QL's because other types of coals are pretty hard to get hold of around here. I also always use ice cold water and ice blocks in the vase.
Maybe I've just got a bad Hookah and it's time for a new one