Given I've had a chance to try the list out, I've had to make a few tweaks.
First of all, I put my Retaliation Cadre into a Dawn Blade Contingent to get those neat to wound and penetration hit re-rolls. Secondly, I had to ditch the Earth Caste Pilot Array, as it was too costly and had to drop one Crisis Suit. I also equipped two of them with double Fusion Blasters to deal better with the Imperial Knights. I also switched the Flamer for my Commander with Vectored Retro-Thrusters to make sure my very costly blob doesn't get stuck in melee. I've also ditched melta weapons and markerlights on the Stealth Suits due to their cost, instead relying completely on the Marker Drones for the Markerlight Support.
For my Auxilliary Formation I have picked the Pirahna Firestream Wing. Two of them are equipped with melta weapons but the biggest advantage of them were most certainly the drones. They were able to create a wall of bodies in front of my army that has allowed me to safely overwatch with all of my units while making sure any other units in the army don't get charged. I've had to face very close-combat oriented armies and Imperial Knights. It was always the latter that were the trouble to me, so I've decided to bring more Melta Weapons.
If placed wisely. I should have 30 S7 shots, 12 S6 and 6 S8 AP1 Melta weapons to deal with the Imperial Knight. 10 of the S7 shots on side or rear (front) armour should make it through, even if 5 of them will get deflected, it makes the IK standing on only one wound. My melta weapons should result in 6 + 2D3 wounds on IK. That's 5 wounds after applying statistical ion shield accuracy.
I'm not sure how much it is the fault of my mistakes or how much it is something in the list that needs improving, but I'm winning only 50% of my battles. If that's my tactical mistakes, I will have to work on them, but if there's something in the list worthy of further improvement, I would very much appreciate your support.
Prosper, as Tau shall.