If I spend a hero point to get a +8 luck bonus to an attack roll

[Papa Chango]

And I hit, does the critical confirmation roll get the +8 luck bonus?

[Bill Dunn]

Yes, you do. Page 184 of the Core Rulebook says:

"To find out if it's a critical hit, you immediately make an attempt to "confirm" the critical hit--another attack roll with all the same modifiers as the attack roll you just made." [emphasis mine]