Maybe it is only in Japan that Baumkuchen is so popular.
Maybe Baumkuchen is this popular in only in Japan.
Perhaps it is only Japan that Baumkuchen was so popularized.
バームクーヘンがこんなに人気があるのは日本くらいかも
Maybe it is only in Japan that Baumkuchen is so popular.
Maybe Baumkuchen is this popular in only in Japan.
同じ意味で文章構成が違う分です。
バームクーヘン＝Baumkuchen
Perhaps it is only Japan that Baumkuchen was so popularized.
maybeの代わりにperhaps、
is popular（人気がある） の代わりにpopularized（一般化された）を使いました。
こちらのほうが社会学やなにかの分析に使われる固めの文章です。
日本 
