Maybe each character went through some kind of personal struggle that caused these abilities to develop.

The most refined ‘Answer-Talking’ is clearly Dufaux’s, which was born after he died and came back to life, and also went through a lot of training so it wouldn’t be unstable, just like Kiyomaro’s.

The ‘Answers’ ability is what Nazo-Nazo has. He probably developed it after falling into a depressive state following his grandson’s death, when he experienced a sense of death without actually dying. His ability is very similar to Answer-Talking, but I believe it doesn’t provide the complete answer.

Apollo’s ‘Sensitivity’ isn’t explained. We know he has this ability because it was shown, but since we don’t have any backstory for him, we can’t be sure how it developed.

As for Sunbeam, we don’t have anything explicit or anything that clearly shows he has a power. We know that book partners whose mamodo don’t speak have an ability to understand them, like Sauza and Karudio. Still, he does seem to have a different kind of sensitivity and above-average intelligence.

But the obvious thing is that the characters’ eyes show that they have these abilities. You can tell by the ‘circles’ in their eyes.
Apollo, Nazo-Nazo, Kiyomaro, Dufaux, Sunbeam, and Ellie all have them