The film has been localized in Taiwan and Russia, but not the United States or other Western countries except for Italy. The fact that it's a children's story about a romance between two adult male characters probably doesn't help its marketing prospects in lots of locales.
Meanwhile, it can be watched in multiple parts on YouTube with English subtitles. There's also an unofficial English dub. At first it was a professional-quality unofficial fan dub, but became the de-facto quasi-official dub when the original production company opted not to localize it and gave permission for the fan dub to remain publicly on YouTube.
Talking to Himself: The unofficial English dub has Tustin Gilmer Macafee voice Gabu and Mei. This means that he talks to himself for 99% of the movie. He also voices most of the wolves and goats, too.
What Could Have Been: Gabu was originally intended to have died before the last book came out to Joss it, much in the same way that Sherlock Holmes was supposed to have died in FINA.