I can clear up the definition provided in the article.

"Yes. And even if the child has initiated."

This is true, but if the child gives consent without manipulation, or coercion, it isn't child molestation for the sake of the definition. Illegal, certainly, but the deciding metric is whether child is consenting.

"Would accepting sexual activity proposed by a child towards whom the recipient otherwise has little regard therefore fit into the definition of "child molester"?"

This is where there is nuance. In short, it's fair to accept that consent is for something specific, generally. For example, a person can take a job, but there are terms and limitations to what they'll be expected to do. So if a child was to show interest in sex and an adult partner did something that the child didn't like, but they continued, that is molestation. Consent can be revoked, and if it is, and the action continues, that would be a means of disregarding the child's interests.

"Also: the initial group of people who may qualify as "child molesters" was "persons". Without specifying age."

Technically, yes. However, I doubt this is very common. If/when it does, it's still wrong and could be considered molestation.

"Meaning that two children who engage in consensual sexual activity to satisfy each other´s respective curiosity and sexual gratification with otherwise little regard for the partner are BOTH child molesters of each other. Correct?"

As long as both feel as if the activity is worth continuing (the ends justify the means), it is not molestation. If one voices a desire to stop and the other doesn't oblige, it is molestation. If consent is revoked by one and the other continues, it would be molestation.