When extra damage dice are listed in a critical effect, do they apply to crit-immune targets?

Question

In the immunity rules, we read:

Immunity to critical hits works a little differently. When a creature immune to critical hits is critically hit by a Strike or other attack that deals damage, it takes normal damage instead of double damage. This does not make it immune to any other critical success effects of other actions that have the attack trait (such as Grapple and Shove).

My interpretation of this rule is that the normal doubling of damage does not occur, but any other listed affects of a critical success do occur. I believe this is the accepted interpretation of the rule, as well.

Now, about the spell Hydraulic Push. This spell reads a bit unusual, because it normally does 3d6 damage (and 5 feet of knockback), but has a listed critical effect that instead does 6d6 damage (and 10 feet of knockback). This is notably different from the standard/basic critical effect of rolling normal damage and then doubling it.

When Hydraulic Push crits against a crit-immune creature, how much damage does it do? And more generally, are extra damage dice listed under a critical effect applied to crit-immune targets?

Answer 1

No

The critical hit immunity text reads:

When a creature immune to critical hits is critically hit by a Strike or other attack that deals damage, it takes normal damage instead of double damage.

So that tells us a few things. Because we are talking about critical hits, it's gotta be an attack vs AC (see this question). So in the case of Hydraulic Push, it is a Spell attack vs AC. So the crit-immune creature would only take 3d6 damage.

However

It's a bit more ambiguous as to whether you'd push the crit-immune creature 5 feet or 10 feet with Hydraulic Push. It seems the strictest reading would say you can push the crit-immune creature 10 feet, since critical hit immunity text only says:

it takes normal damage instead of double damage

It doesn't actually specify that its immune to other effects of the crit, such as weapon specializations or the Fearsome rune (and similar things), only that the damage isn't doubled.

I, as a GM, simply treat anything that targets AC as a success max though (and not a critical success). Much easier to manage at the table, firstly, and makes intuitive sense, even if the specific rules may say otherwise. Further, the critical immunity rules state:

This does not make it immune to any other critical success effects of other actions

Which seems to imply immunity to all critical success effects of a critical hit.