no, minions in general do not benefit from +% skill damage or -% enemy resist affixes unless specifically set to do so (hydra and traps)
they will however benefit from the Sunder effect on flame rift, only if you have flame rift in your inventory before you summon the tainted, swapping it on afterwards leaves them with no sunder effect even though its in your inventory.
for standard setups this means tainted can hit fire immune enemies at 78% resist (95 from sunder, -17 from conviction merc), unlike a player who can slap on 50+ pierce
Since when does - resis effect traps?