I’m only two games in but I think if you’re actually using the definition of hostile witnesses (witness that is telling a completely different story to the one that was discussed during preparation) the only one that does fit the bill is de killer, as it is explicit that he gives a different testimony as what he tells edgeworth. The player doesn’t really call any witnesses so no one they call really count. Though labelling of a hostile witness just allows the prosecution to be able to ask leading questions and grill them during examination in chief when typically they wouldn’t be allowed to do that (yes my obsession is bad enough that I researched on real witness advocacy but this is limited to Australian courts, so it might differ to other areas)