I expect the introduction of a new group of Dathomir witches is planned for bigger things down the line
I mean these ones might not all even be dead.
The clearly got "taken out" by the backlash of their mind-control being turned off, but did that kill them? It seems unlikely. More likely they're all seriously unconscious. Now, there's a lot of fire and smoke, so they may well die of smoke inhalation and so on, but I didn't see any evidence that the Jedi actually checked they were dead. Indeed, only Sol seems to even have seen the bodies, and he just just rushed over them - he didn't check any of them. He presumably then reported back that they were dead, but Indara is just assuming he was right or "right enough" that it wouldn't cause a problem with the Jedi council.
The only one we know is dead almost for certain is Aniseya. Any of the rest could potentially turn up again. Double-especially Koril who wasn't even with Team Mind Control. God knows where she was.
Mother Aniseya started it by getting into Torbin's mind and playing with his desire to return home, so as soon as he realized the twins would prove the Vergence was real, he could not stop himself and had to go and get them. So in a way, she brought about the witches' doom onto them.
No.
Flatly no.
The Jedi decided to interfere and to act like colonists/empire-builders who decided that they "knew better" than the locals. Sol followed some kids, and instead of reporting back, literally broke into a fortress to sneak on them, and then came back and gave Indara a lurid depiction of what was going on, something Indara clearly knew, but decided to kind of go along with anyway.
The Jedi as a group then, instead of negotiating or make any attempt whatsoever to peacefully contact the locals, broke in en masse and armed, and barged into the middle of a ceremony, intending to and succeeding in causing a problem. This is the equivalent of a bunch of armed members of one religion breaking into the church of another during a coming-of-age ceremony and attempting to the threaten them. The idea that the Jedi presence there was in any way legitimate is laughable. Only the colonial mindset of the Jedi and their concerns about "witches" and so on even gave them the excuse to do this home invasion.
Frankly Aniseya was incredibly reasonable. She found one weak Jedi and messed with him, but hoping to make him force them to leave and to show her power so the Jedi didn't just start pushing them around further. Her actions did unforeseeably contribute to the tragedy that unfolded, but there was one individual who actually caused the whole thing!
So let's be clear, this is
100% Sol's fault, because it all stems from his obsession with this little girl (which seems to stem in part from feelings of insecurity and a desire to be part of a bigger story), and he had several opportunities to "throw the brakes" here and unnecessarily committed murder in someone else's house because of his obsession with that child (a child he couldn't even tell apart from her twin, I note). The most notable opportunity to throw the brakes being that when he reached the fortress after the padawan did, the padawan had no idea how to get in, and Sol could easily have said "Well, let's wait for the ship to get here", but instead, showed the padawan how to climb in and cause a problem. He then murdered Aniseya because he decided that him not understanding what was going on was a good enough excuse for murder (absolutely leaning into the worst ACAB stereotypes), even though he had absolutely
no right to be even be in that place (and was
directly disobeying multiple layers of orders) nor interfering with those people, and had been told very clearly to
stop the padawan, not
help the padawan.
I can't blame Indara for whatever she did with the mind-control of the wookie, she'd probably never encountered force-magic like that before so was freestyling in how to stop the mind-control. Also, as noted above, I rather doubt that the sisters died from that. More likely the ones who are dead died from smoke inhalation and/or fire and/or falling debris. But Indara became frankly a criminal when she decided to lie to the Council in order to facilitate essentially kidnapping a child, and essentially for the sake of the very sentiment she condemns Sol for - "You can't destroy her dream" (note: Indara doesn't even really believe it is Osha's dream only hours earlier, she thinks and even says - correctly - that Sol, a grown man, manipulated Osha, a little girl). So instead of even following protocol, she just makes up a story, essentially condemning all four Jedi to "live a lie", which is just a completely terrible decision on every level, even that of Osha's future. It's really a self-serving position on Indara's part. If Sol threw himself at the mercy of the Council she'd also look like a complete dunce who had no control over the situation and let herself get pushed around by an emotional non-Master Jedi, so might have faced some pretty bad consequences. Again, very colonial of her.