Not only that, but they still seem awfully slow to actually use their heals in combat.

Right? If I we're the lead designer of the Advent, I'd redesign it to be a sphere and have swivel chairs for the dumb psi-integrate that can't look out the side window.

forget the idiot that never thought the thing would ever have to turn

With TLT  on the field potentially preventing most if not all of the advent fleet from casting abilities(very possibly during a Marza ult) methinks we shouldn't be too hasty to trade away the ability which can potentially make a key capitalship immune to said disable.

That said it certainly needs to be more flexible & responsive then it is now.  Removing the channel was a good start, but it really needs to be made omnidirectional.  Balance accordingly with AM cost & cooldown, but the lack of responsiveness is currently still a bit of a deal-breaker.

On the plus side they finally fixed/changed it so it works on auto cast both inside combat, and out. I do agree though that perhaps it could use a buff so it doesn't need to face its target.

In my own personal mod of the game where I've modified a laundry list of things, I reworked Perseverance and Ruthlessness in a similar manner.  Perseverance now endows a non-stacking buff of 20 hull/second but also instills an infinitely stacking 5 hull/second buff, allowing multiple Dominas to heal the same target for an increased rate.  It also does not need to face the target.

Ruthlessness was modified in the same manner, dealing 3 DPS and an additional .09 DPS per ship and now IMO they are significantly better abilities.

Unless I'm mistaken, it must line up precisely.

I'm not sure about the channeling. As I said, I tried to get a Domina to heal a corvette and after 5 minutes gaves up watching.

Incidentally Suppression doesn't have a channel anymore either.  Which means domina can potentially keep multiple enemy frigates locked down at the same time.

Unfortunately, with the current fear of feeding titans, the enemy may not have many front line frigates  by the stage of the game domina comes out.

That said, make perseverance a bit easier to use when it's needed and the Domina will be an amazing addition to any advent fleet.  Heck, I could see it working to cut 15-30 seconds off the duration to make it omnidirectional if need be.  better to have a short duration buff when you need it then a long duration buff which is prohibitively difficult to cast when it's needed.