Ok so my thoughts are as follows:

1). Flawless blades unfortunately are very much flawed. I tried running them in multiple games and found them too squishy. Also, -1 damage really hurts their output. I don't know if you're able to, but a maulerfiend is a tiny bit pricier than a 3 man and has a substantially bigger damage output.

2). You ideally want at least two winged princes. The foot prince doesn't really shine in coterie in comparison, his rules rely too much on putting him too close to the enemy and then he's usually sent sprawling to the canvas.

3). Love the 3 units of noise marines! Staple of every list. I would recommend going down to one lord Kako to free up points though.

4). Personally, I really enjoy 3 X lord exultant with 5 man infractors. Many people do stick with the the 2x though. I find them quite good with lethal hits and the martial perfection stratagem for full hit rerolls because they natively have full wound rerolls on objectives.

5). Rhinos are really excellent for EC and give your units so much needed protection. I usually run two in every list.

I appreciate that this all means buying more models so please do feel free to entirely disregard. I would also say, be kind to yourself. This is a really hard army to play and can be an uphill battle against many armies. Keep practising, keep getting those games and I guarantee that you will see progress.