As usual whether you want to live in Japan or not is dependent on the language. Despite the fact she is extremely intelligent, surrounded by foreigners it would be difficult to learn not only Japanese but the culture as well. The language seems to be no. 1 reason why foreigners decide not to live in Japan. That is understandable. Yllah should live in a country where she feels most comfortable and happy.
Yllah is very peculiar name. But it sounds beautiful. Congo is one of the countries where the official language is French. In French language, they don't sound "R" like New Yorkers. But personally, she speaks like an American. I like her as much as Mariya -Sensei.
厳しいことを言うと、「日本に本音と建前がある」と思っている間は、日本人と日本を真に理解していない、と言うことです。 Strictly speaking, as long as you think that "Japan has honne and tatemae," it means that you do not truly understand the Japanese people and Japan.