Do you think the Citadel Council races plus the Angara can liberate the rest of Andromeda?

No,

Take away the scourge, Archie would have destroyed Ryder and his/her little ragtag group of misfits at meridian. Even after gaining Meridian, what defenses do the Initiative have against the kett? They know the location of all the outposts, the Nexus and Meridian. Since Archie knew the location of the Nexus, I wouldn't be surprised if the kett know the location of Aya? Would Aya be able to defend itself if the kett decide to attack with a large force. If Primus sends word back to his homeworld about what happened, would the kett bosses send reinforcements? Most likely, to replenish the forces lost in the cluster, and how long will that take? Not as long as it would take for the Initiative to build any kind of force. 

Another thing is Archie had the rookie in his grasp with the immobilzation field. At that time I would have fired at the salarian ship destroying it and possibly the tempest. Eventually gets the information from Ryder about the sam-in-the-head thing. He attacks and destroys the Nexus. The initiative is no more. 

If I was in Primus spot, I would attack the Nexus. Take what ships he has, and attack. I'm sure within a few minutes the Nexus would be in ruin. Or better yet, invade the Nexus, like they did to get on the Hyperion, to take control of the Nexus. They kill the one's that fight back. Eventually they start exaltation. Who would come to the Nexus aid? What would an outpost do if the kett attack in force? They would crap all over themselves.


and yes.

Meridian. No one knows its true potential. Its the size of a small moon. It could be similar to the death star. Its possible there is a very large fleet of ships, fighters  that can be used to fight. Even if there's plans that be used to build ships for attack purposes, that would take a lot of time, even with the robots helping. There could be plans to add weapons to the ships seen in the game. Would that be enough? 

And yes again.

Its possible that a force from another cluster comes by doing some exploring when they encounter the angarans and Initiative. They become buddy, buddy. They talk about their species and that they have a massive force that can help deal with the kett. It will take time for it to get to the cluster. Once they rid the heleus of the kett, they can, with help from Initiaitive and angarans, travel to other clusters to get rid of the kett, if they're in other clusters.

while it's true the angara have been fighting the kett for decades, that only gives them combat experience against the kett, though actual actionable intelligence has been fairly rare outside of the planetary conflict on voeld or kadara. the angrara might know a lot about how the kett fight, and what the local targets look like... however, beyond the fightning on voeld or the former kett presence in kadara port, cluster wide intel on the kett is still in very short supply.

You don't know if the Kett rule all of Andromeda. Perhaps they're pretty small compared to other empires/federations. They could be just one of many interstellar groups.

I have a strong feeling that the Kett are very powerful on a local level rather than on a galactic level, purely because of the tech they need to employ to travel between clusters, and because the Andromeda galaxy is vastly larger than the Milky Way. That doesn't make them less of a threat, but it means there are likely rival powers to be found.

yeah I think they're moer of a local species than a galactic one as while genetically they may be more advanced technologically I don't think they are. I mean look how fast SAM got Ryder and the Angarran team into the Kett base to rescue the Moshae for example by hacking their systems if they were that technologically advanced they would have had safeguards against things like that especially while studying the Remnant. They may have control of 1 or 2 clusters but that'll likely be it. They I think just like to talk themselves up bigger than they are I think.