I do agree that the Aurum Vale is kind of a healing challenge for a not veteran healer XD
Especially for a young whm (the dungeon is a lot easier as scholar)

This is a lot harder for a whm because it's the slowest healer, with no "Oh Shit" button and no DPS window or risky one.

If you're beginning I would advise to not DPS at all.
Healer DPS is only for veteran healer who are confortable with their healing power and timing even of they got squishy tank (or idiotic war)
Since there is a looooot of poison and heavy hit on this dungeon you need to prepare heal and cleansing at EVERY step.

The first boss is check your friend and keep regen up while pampering your tank
The second boss is look out for the eyes and be prepared to rez/esuna if necessary (and stay as far as possible)
Last one is the same as the first one, with less heavy hit but more DoTs from the boss (check the fruit, heal accordingly and prepare one holy for the eggs)

This dungeon is really easy when you know all step and dangerous hit

I was terrified as Blm or whm, i love it as smn/SCH

The thing is be careful, watch out for your mana do nooooooot panic, one dead is fine just plan your healing carefuly