I do feel that many CC members' English isn't that great, and you are probably right in that their lack of English ability is contributing to the feeling of neglect.

In Japan, it's deemed to be a little rude to ask the customer to repeat what they've just said, so it could well be making them more reluctant to communicate with non-Japanese speakers, in case they are deemed to be rude if they need to ask them to repeat themselves. Unfortunately this in itself can be deemed to be rude as well - in a way, they have a difficult job, although you could say that all international CC members should be fluent English speakers (but that's not as realistic or easy as it may seem).

While I am a fluent Japanese speaker, I tend to be lazy (especially when I am tired) and end up mostly speaking English. On some flights, I don't speak any Japanese except 'hello' and 'thank you' (just to be polite) but I find JAL service to be superb. I also feel, however, that I know at the back of my mind that I can speak to someone in Japanese if necessary, and I suspect they know it too, because I speak Japanese without any foreign accent. So maybe my experience is not so representative of other people's experience.