Shattered Pixel Dungeon- v2.5.2

So I was playing a game with wand of transfusion a while ago, but I forgot to ask questions about it here.

In the prison area, the guards and the thieves are undead monsters now, so they take damage from the wand of transfusion. However, the necromancers also take damage from the wand of transfusion. The description for them says that they are apprentice mages from the surface who came to practice their craft. Wouldn’t that make them non-undead enemies, despite specializing in summoning undead creatures?

Also, Tengu appears to be charmed from the wand of transfusion instead of taking damage. Is Tengu not an undead creature, despite the guards and thieves being undead?

Also, the machines like dm-100 are susceptible to being charmed. Obviously they are non-undead creatures. However, they are also non-biological creatures. So should they be vulnerable to being charmed?

Thank you for your help.