i never ever had 5000 hp at level 10 with my sedna not even later. 5000 hp is possible but very unusual so this numbers may be theoretically correct but practically wrong.
The most popular map is cataract. Blood of the fallen, nimoth's, and banded armor gives you 4768 HP with an HP flag (but it costs a whopping 2050 gold!), if you get any other HP items at all you easily break 5k. Don't pretend 5k is an outrageous number.
that's bullshit. her own healing spell healed many times more. you seem to very overestimate the healing of the priests. on any level timestep i healed with my own spell at least arround 1.5 times as much the priests done. and the bottom of the curve was achieved when buying the high priests arround level 5.
Two things. First, there's no way you have mana to heal every single cooldown unless you give up pounce altogether, which combined with your how HP makes me believe you simply never played Sedna to her fullest when the priest bug was in the game. The whole idea is you stack HP and save mana by relying on priests so you can pounce more. Second I already showed 5k HP at level 10 is quite easily achievable and there's two priests so you can be healing yourself and whoever you're farming with. In many cases it's an UB and UB breaks 5k more easily than Sedna.
High Priests could easily outheal Sedna prior to this patch. That was the whole point of the build, Sedna's direct heal was the backup heal, not the primary.
you seem to forget that bishops have a higher base heal than high priests!
What does that have to do with anything? It's still only 22% with healing wind, a full 8% of ones total health less. A 36% reduction is very considerable.
Also I'm not sure who said it, but it's correc that the priests only heal DGs once every 10 seconds. Their heal goes off every 5 but there's an invisible debuff on DGs that prevents receiving heals more than once every 10 which I forgot about when I said 5.