I've found Venoms significantly more effective for their points than Raiders. The Solitaire is both real fast already (remember, he can Advance every turn without losing anything thanks to Rising Crescendo, so in practice he's only .5 inches behind your transports on movement), and a Character, so he doesn't really need the transport space you appear to be leaving open for him (and I don't think he can go in a Raider, as he is not Drukhari Infantry.)
I also would advise taking Mandrakes in place of barebones scourges- they are the more effective options for the point cost if you don't take advantage of the large number of special/heavy weapons slots that Scourges offer. Mandrakes are noticeably more expensive than barebones scourges, but much deadlier and significantly more durable (to shooting attacks, anyway).
Honestly it might be worth dropping the Solitaire entirely- with a Succubus and large numbers of Wyches, some special weapons on your Syrens would achieve a very similar effect at a drastically reduced points cost.
If I were optimizing this while keeping it similar in terms of playstyle, I would:
-Drop the solitaire from your army. You've got enough assault strength without him, and he's really expensive.
-Exchange one of the raiders full of Bloodbrides for two Venoms with 5 Bloodbrides/Wyches aboard each (as points allow). This also gives you an additional unit champion weapon slot, and additional gladiatorial weapon slot.
-Swap a squad of Scourges for Mandrakes. Both, if you can fit the points in, which should be doable if you drop the Solitaire. This gives you considerably more killing power against things with decent saves (and vehicles).
-Take some special weapons on the unit champions of your Wyches and Bloodbrides, and gladiatorial weapons. That will give them extra killing power at a much cheaper cost than the Solitaire.
Hope this helps! Definitely keep the Voidraven, it provides durable, mobile anti vehicle power, and you need that.