If i'm not wrong, the character screen lies to you. it displays the fire damage assuming you are using a melee weapon (even if you're holding a bow)
+spell damage does not apply to ranged attacks. i'm pretty sure the mechanics to these weren't modded on hell unleashed.
you can check this link from another diablo2 mod
http://modsbylaz.14.forumer.com/viewtopic.php?t=1150Taken from the link:
+% spell damage also works with passive elemental damage sources, but only on direct melee hits.
Passive elemental damage sources include items and skills that add some sort of elemental damage to your weapon attacks, but do not allow you to attack anything with the skills themselves.
Examples: Snake Stance, Plague, Curare, Way of the Phoenix, Kraken Stance.
A melee hit occurs when you swing your weapon at something and that something takes weapon-based damage. This does not include any weapon-based missiles or splash damage (eg. Crucify spikes, Retaliate nova) that may be emitted from the target. Elemental missiles are of course considered spells.