Hi Camila, I think I can explain this according to my experiences.
I was born in Asia in my current life and I feel that I lived most if not all of my past lives as Europeans. I do agree with your findings, but I believe most of the scientific researches were done by North American or European researchers and based on memories of people with European culture backgrounds.
Based on my experience in Asia, at least in the place I lived, nobody believes in reincarnation or even thinks about this idea. As they don’t believe in reincarnation, if anyone claims to have past life memories, the person would either be mocked or be considered as crazy. If a child ever speaks of their previous life, their parents probably thought it was nonsense.
Despite that, I did find some sort of evidence that most of them were reborn to the same or similar culture. They do seem to have strong interest in their culture and similar cultures of neighbouring countries. And many of them are fascinated by the history of the place. One example is that a classmate of mine was obsessed with a particular time period in the history of the country, she could even write in the old style language that was no longer used. I also noticed that unlike me they have little interest in European culture. I do think that the majority of Asian people lived their past lives in Asian countries.
As for why most people on this website remember European past lives, it is possibly due to the fact that most of them come from North America and Europe. And Asians might not be able to access this website because of lack of understanding in English. For example, if my parents noticed I had past life memories as a child and wanted to search for answers, they won’t be able to find this website or post anything here because they know little English.