I have a suggestion for allowing the zombies to do more than 0-3 damage per hit, basically give them a weapon item that has short range and is invisible, called zombie claws or something, could do like 5-15 slash damage.
Also zombie parties of like 200 would be good, some have said it'd be annoying but you have to consider that according to the mod there's only 100,000 humans left (I'd like to recommend that be changed to like a few million, just seems more realistic, like there's probably that many alive in the area where the game takes place, so I'd guess the world has like 10 million left out of a previous population of over 7 billion), meaning there's over 7 billion zombies in the world probably, around 100 million of that 7 billion living in the southern United States, so it'd make sense for there to be big roaming parties, but make them rarer, like have a decently large number of smaller parties of like 5-20, and then have the occasional horde, and as someone recommended the horde could be done like phantasy calradia, a notification saying something like "a large horde of walkers has been spotted near (location)"
Also there's not enough bandits imo, I've had trouble finding many hostile parties compared to native and other mods, where certain areas may have a lair or two and a dozen bandit parties around the area of the lair, here I'll just see one out of the corner of my eye every so often really.