The presence of Fox P2 does not factor if there is no linguistic exposure between 6 and 60 months - the exstimated wild children of France in the 19th C had no ability to make effective speech even in their teens. They had, at best, vocabularies in the couple dozen nouns and a couple of verbs.If it is a human they already have the capacity for language due to the foxp2 gene, so we could essentially create a common language, it would take some time though. Culture and language are essentially adaptations to our environment, higher concepts would likely be more difficult, rather than more basic ones.
Neurobiology has certain key limits on speech. Such as, if not exposed to certain vocal sounds in meaningful speech before age 5, one will struggle to hear them forever - hence the difficulties of most whose early languages are non-slavic have issues lifelong ever distinguishing one or more of the rarer sounds of Russian. Intense neuro-linguistic programming can work to about age 12... but it requires intensive interventions. When I took Russian, the only sound distinction I had issues with is that ы & у are hard for me to distinguish in the Petrogradskoii of my professor - and only four of us ever got it by anything other than rote memorization.