Does it do anything relevant to the game? If Z'ant gets pissy and goes hostile Charm was to late right?

I believe the spell has 3 functions:

1. If an NPC is neutral (for example, if you are caught stealing from Lord Braffit), this spell can turn the NPC friendly. (I don't know if this applies to RFS-81; androids might be immune.)

2. Casting this spell does count as practice for the appropriate skills, and there is no practice timer. (I believe that, if successful, you may need to exit the encounter and talk to the NPC again to continue, but I am not sure.)

3. If Charm backfires, the NPC may turn neutral or hostile.

If Z'Ant (or any other NPC) is already hostile, it's too late to cast Charm. However, if you can hit the NPC with Turncoat and end the encounter, you can initiate conversation that way. I believe you will have to do this each time (and, though I'm not sure, you might need to use a quest item to initiate the conversation without Z'Ant going hostile on you).

As always thank you!