okay sorry, been doing some searching around. I still don't think the full rules for the titan holofield have been put forth here. My google-fu found this:
http://www.thedarkcity.net/t13096-new-ia-s-revenant-titan-rules
had a screenshot posted of the revenant titan holofield rules from 2015. Says the holo field effects happen after hits but before armour penetration. If that link is accurate, then there is no conflict at all. Karn's rules always hit on the 2+, but before penetration rules are rolled the titan holofield may nullify some of the hits.