Ok, bit of an assessment of our new Coven members...
Sumeragi Kaguya
Primary Virtues: Highest is likely Temperance. She's a rather patient person and she maintain a great deal of self-control - even when Zero's "true nature" is revealed in canon she keeps her calm in spite of being visibly upset. Four dots there, at least. Her next most important one is probably Compassion. She's a nice person. Three dots, maybe four.
Attributes: Her Exaltation probably focused on Social Attributes most - probably four dots in Appearance, and I'd guess her Charisma might be five dots (canonically her stats according to Lelouch has her Charisma maxed out), with Manipulation coming last at a likely two dots. Next will be her Mental Attributes. Her canon intelligence rating is quite high, only beaten by Rakshata, so maybe four dots, with Perception and Wits being three dots each. Physical stats come last, with her likely being identical to Milly with Stamina at three dots and the others at two.
Motives: Pretty much freeing the Japanese people from oppression. And now quite possibly marrying Lelouch. On the former count she's in a good position to make it easy to work with her, and our goals align with hers pretty well.
Role: Likely helping us a lot on the social side of things, especially with the Japanese. Opposite of Milly, who will be operating on the Britannia side of things. Also an important role will be giving us lots of lulz as she makes things awkward for Lelouch.
Rakshata Crawla
Primary Virtues: I'm not sure if she has any particularly high Virtues. Conviction maybe since she's willing to build weapons for the sake of world peace. She wouldn't be only one dot on anything, though, I think.
Attributes: Mental stats would be her primary ones. Intelligence is likely maxed out. Social stats are likely second, likely with Appearance four and her Charisma being higher than Manipulation. Physical again I'd guess would be identical to Milly.
Motives: Ending world conflicts so people can focus on important shit, like medical technology. Again, should be easy to work with.
Role: Building cool shit. The Guren will have magical materials. Being an Infernal, she's got more potential than Lloyd, so she may surpass him in terms of what she is able to make.
Hyuga Akito
Primary Virtues: Valor. Definitely Valor. Conviction after that, likely.
Attributes: He's the Slayer, and he's apparently been punchsploding Knightmares, so physical for sure. He's had three years, so he may well have maxed his physical stats out. I'm not sure whether he'd be social or mental after that, but it doesn't matter as much for him since his job is to punchsplode the enemy.
Motives: If he hasn't found and murdered his brother yet, then killing his brother is likely his primary motive. If he's done that, well, who knows? Working with him might be a bit difficult, especially if he or Leila are still invested in whatever is currently going on in the EU.
Role: Punching the enemy.
Leila Malcal
Primary Virtues: Compassion, most likely. Either Temperance or Valor after that. Her Conviction is probably two dots.
Attributes: Social first, with mental second. Probably more Charisma than Manipulation, but won't be bad at either. Physical will be lowest most likely, though she will make up for this with some expertise in Martial Arts as she's trained in Judo.
Motives: If she's similar to canon, she's at least got an Intimacy if not a Motivation for helping the Japanese people stuck in the EU. That'll help with working with her, though again whether she can come to Japan or not I don't know.
Role: Secondary commander. She's not Lelouch, but she's no slouch when it comes to war.
There shouldn't be any issues with having Kaguya or Rakshata being close by to help us regularly. And let's face it, Kaguya will probably enroll in Ashford Academy to be closer to Lelouch. Hijinks will ensue.
The other two might have to be in the EU for a while. Hopefully Ligier is going to be ordering Akito to come to Japan to help us out as there would likely be other agents of the Reclamation in the EU to help fend off Britannia, because we really need a combat focused Exalt on our side to balance out the Coven's Social and Mental focus. One possibility is that Leila will be able to convince her superiors that supporting our rebellion in Japan is for the best - there's no way the EU can conquer Japan given it's geographical location, so helping it become independent of both Britannia and the Chinese Federation is in their interests, especially if we throw in increased exports of Sakuradite to them to sweeten the deal. Britannia would similarly be denied the largest source of Sakuradite, which would stall their own army. Leila and her unit could be sent to Japan to aid the Black Knights for that reason, and it would be a good cover story for who our secret international backers are.