Do you like the Cult army style?
Adding some shooting units would help you a lot, some Ravagers or Razorwing Jetfighters would help. Ravagers tho are not Cult but Kabal only where the RWJF is Cult.
If you want more Coven that is fine That is more Melee tho and it is a "different" melee type not fast and heavy hitting vs, fast and large attacks. You can do a 1-2 punch army, Turn 1-2 tie up and kill some things, turn 2-2 get heavy hitting units in melee.
IMO tho i think you need shooting for Anti-Tank, Scourges is another option, 2 Boxes so you can have 2 units 1 of Blaster (always good) and maybe 1 with HWB (more for heavy tanks and ones with Invuls)
New to Blogging, just starting https://maddpaint.blogspot.com/
Dark Eldar 10k+
AoS: BoC 8k, CoS 3k