Café de Nuit

It suddenly hit me: why aren't the Vistani trying to take out the Gentleman Caller?

Are they simply unaware that he's been deliberately siring his offspring, some of them Dukkars, by targeting women of Zarovan blood? With all the knowledge they can access, how is that possible?
Are they afraid of tackling him directly? Then why not tell a lot of adventurers about the demon and his weaknesses?

Guess it boils down to lack of content beyond the GJ and nothing else tbh. Really curious how the new RL product will treat major NPCs of RL cosmology, but then again I'd lie if I believed for a second that's what is going to happen, knowing everything is gonna be an Island of Terror after that.

They are in my head-canon; he can't be divined so easily thought.

He could be the Ancient Enemy of the Vistani, the one they came to the Demoplane to escape from. Though I doubt this is the case.

He is the transfixed soul of the First Dukkar, the one who destroyed the Vistani Kingdom in Invidia and forced the majority of Vistana to wander forever.

I would expect that his Reality Wrinkle protects him a bit from vistani Sight, which is somehow linked to the fabric of the demiplane. Maybe they will eventually catch on, but that should be enough for him to at least have started his plans before they put things together enough to go after him. The vistani going after him is a good plot hook. But them foreseeing what he'd do and stopping him before he starts isn't as compelling. Thus, enter the DM-tool/Plot device of the Reality Wrinkle.

From an OOC standpoint it seems like thread of Malocchio working for the Gentleman Caller in gathering Vistani women was kind of let go. In any case, one could argue the GC meddling with the Vistani would have not been necessary had they not bound Malocchio to Invidia- as Mal could have teleported himself- along with the GC, right out of Ravenloft. So in character if you wanted to go with and explain any sort of hesitancy for direct action against the GC, perhaps they fear further retaliation from him or his brood.

On the other hand, you could interpret that the participation of Madame Fortuna and the Skurra vera in Carnival as an example of the Vistani working against the GC. The existence of the Skurra vera masks would seem like something that would require a lot of time and resources to develop and perfect.

The existence of the Tribe of Hyskosa complicates Vistani participation in the GC's activities. If you go by the revelations of Gaz V and further descriptions in Champions of Darkness, they are meddling with Azalin Rex's exploitation of the GC's children for his own end as revenge for indirectly causing their downfall. How the rest of the Vistani might view this rogue clan's activities would be interesting to consider.