Fixing Every Healer Job

[Shurrikhan]

That depends on what else is adjusted really.
What if SCH's shields were adjusted to make them advantageous enough to warrant using Covenant over Dawn or Blessing? Say that Addlo now reflects back 140 potency worth of damage on hit, as an example. Most shields would be gone on 1-2 hits from a boss. Between the mitigation and buff to the shield granted by Covenant, if that was able to make it 2-3 hits instead, would that not be worth it?

I like your thinking there, but unless an affected shield would otherwise have just barely broken on the second hit, nothing in the order of 10% bonus healing raidwide (Covenant), or even a Divine Seal (+30% Spell healing) for oneself is going to make a 50-200% increase in hits taken before said shield breaks.

More simply, though, I think you'd simply have to rework Covenant. As you'd likely want to do with Aetherpact anyways (e.g., to cost 10 gauge per 3s tick of healing thus provided). I'm also unsure if I like Seraph being on there at all, considering it grants more than 75 gauge worth of resource (the benefits, essentially, of all the other spender options) and thus becomes a non-option, a mere CD that at best has some (arguably wonky) margin play by which one can't use other spenders when coming up on Seraph's CD because the latter so outweighs the others' efficiency.

Finally, the abilities still have CDs so isn't not as though the abilities will even conflict with each other any more than they currently do.

That seems a cop-out, unless said CDs are at least less than they are now.

Imagine, for instance, if Lustrate, Sacred Soil, Indom, Excog, and Energy Drain all had CDs of a minute or more. Due to attaching Broil to its generators (I'd have to hope at a mere 5 per, at least, if you don't want it capping in under 20 seconds), your earlier spitball generation would cap the Faerie gauge roughly per 30 seconds, while likewise offering 3 actions worth (25, 25, and either 50) of spenders from cap. You'd be unable to spend the resource as quickly as you build it if you left no (nearly) CD-less options.

Or, more generally put... If the SCH can't leverage the situational advantages of one ability over its alternatives (or avoid being budgeted less advantageous abilities) beyond what it could before then why have the shared resource at all? If the system doesn't cause new considerations (i.e., conflicts and affordances), leaving us just doing as we did before, then it will be mere bloat.