It's a pity that there are only two ranged units in the undead army - skeleton archers and liches. I would have liked to have more and stronger ones. But Inferno is unlucky in this regard: only one biara, and even the cave demon can only shoot twice.

Each race has almost two ranged units, except for the Academy, which has -3, and Inferno, which has 1 (but with a large number, they are better than the two ranged units of humans). As for the fact that there are few ranged units in the undead army, I think this is nonsense; they have more than enough ranged units. There are ALWAYS a lot of skeletons, and there are also enough liches, and they hit several units depending on the formation.

Added 7 minutes later
as for the topic itself, I think that a good player should be afraid not of a ranged unit, but of a unit that cannot be countered. In Heroes 3, these were nagas; there are many of them, they are strong, they move well, and they hit hard. Also, hydras, but they are generally nasty if they manage to reach you:)
by the way, regarding skeletons, playing against the undead on a large map and not trying to eliminate them in the first 2 months will be a losing strategy (and eliminating them in such a timeframe on a large map is practically impossible). I think that, given that skeletons now shoot, necromancy should be simplified instead of raising them.