I don't really understand...
Does the result of the attack dices are counting with the D12 dice ?
The way you telling may be think of it.
"The Temple gets more powerful as the Priestess gains temples in play"
Ok if they have one temple the temple make 1 dice damage, if they have 4 temples it make 4 dices that's ok... but how it could "adds more to the d12 roll" this way ?

If I check the rulebook it's say :

Add or subtract all of these modifiers from the number of
dice listed in the attack bar.

okay for example the way I understand it is if you cast a fireball on a creature you will roll 8 red dices, but if the creature have flame - 2 you will subtract that, so roll only 6 dices.

Roll a number of dice equal to
the final, modified attack value.

Okay its clear I roll two 0 one critical 1 one 2 and two critical 2, yeah I'm pretty lucky today
So the creature will take 3 damage and 2 more damage minus it's armor.

If the attack has any possible
additional effects listed in the attack bar (always shown as
an additional effect box with a d12 icon), also roll the effect
die at the same time,

Ho yes it was a fireball after all, it could have burn the creature !
So I roll my D12 dice and make 11 It's a 2 burn !

and add or subtract any modifiers to
that roll.

Too bad, the creature have flame - 2 so it's only make 9 and a single burn.

That's how we playing actually, did it's right ? Did I have to my 5 damage to the D12 and make a 14 ? I this case if the creature have 2 armor did the 2 single damage count on the D12 result or not ?

The flame -2 only modifies how many red attack dice you roll. Any modification +/- to the yellow effect die will be clearly stated on the card(s) in question.

So the temple of light gets +1 on the yellow effect die roll for each other temple in play (I think) meaning it is always 2 outcomes (9-10, then 8-9, then 7-8 etc.) which result in a stun, but the number of outcomes that daze increases with each additional temple in play. (11+, then 10+, then 9+ etc.)