I downloaded the mod last week, started the campaign. Adored the changes and got addicted. As I progressed, I initially liked the NPC's being as tough as they were, but after a long day of work and time to relax, I do not want to spend what little time I have killing a squadron of NPC's who almost never die. Like any other game, you have your hardcore and soft core gamers, you want to attract both, I nearly just stopped playing the campaign due to this frustration, but mustered enough willpower to hunt through the forums to find a way to enjoy the mod. Thank you Sig for making the enquiry and thank you to the fella pointing out where the difficulty can be changed.
Maybe consider a in-game built option to adjust single player difficulty.