Question: Why does it seem that there are no records of Buddhas and Bodhisattvas manifesting in non-Asian countries?
Answer: They do manifest in all manners of form needed to reach out to all kinds of beings, even if there are no records of every kind of beings reached out to. This is so as if there are no clear Buddhist references in truly ‘foreign’ communities in the first place, such records would not be made sense of accordingly, in terms of Buddhism.
As beings need karmic affinity with Buddhism, the Buddhas and Bodhisattvas are always trying to increase it. The less affinity there is, the harder is it to embrace the Dharma. This is a reason why being reborn Asian is generally easier to learn the Dharma, due to Buddhist cultural influences being more prevalent in Asia, making it easier to relate to.