As I took it, the problem with the script was half-and-half: The Japanese show doesn't seem to have been quite as characterful as the UK version. Even the soundtrack is bland. I think it was quite stodgily translated as well, though.
But the main reason that the show failed to get traction in Japan was that it'd all been done before with giant robots and it'd been done better in live action. For example, X-Bomber ripped off quite a bit from San-Ku-Kai. That was something that a western audience couldn't really perceive.
I've also heard people say that the Japanese don't have as much of a natural affinity as we might towards Supermarionation, given that many of us grew up hooked to Thunderbirds.
I don't happen to think that's true, mind you. The Japanese produce vast quantities of models and all sorts of things related to Thunderbirds that are only intended to be sold in Japan. Just check out Hobbylink Japan's website. They also funded one of Gerry Anderson's later shows; Firestorm and produced Thunderbirds 2086 as well as their own comic-based sequel to UFO. So that idea doesn't quite sound right to me.
The reason Thunderbirds 'owns all' is that there is no similar show made in live action and no Supermarionation has ever been better-made.
To a western audience, Star Fleet is unique as well. So, both Thunderbirds and Star Fleet both hold up well at our end in that sense.
Whereas, the Japanese had lots of shows along the same lines, only those were better because they were live action.
The other point is that Star Fleet lifted a lot from Star Wars, which I think we see as something cute and familiar.
I don't think the Japanese reacted the same way. I think they saw that combined with the above as too much plagiarism.
I rescued a really good article that Shane wrote on bigdaix.co.uk and added it to my site's database.
It says the same thing, pretty much only better: http://www.xbomber.co.uk/?page=news&id=116
Shane's site was offlined about a year ago so I merged everything on there into this site. I was actually hosting it. There was nothing wrong there but his domain name, pointing to the hosting server expired and I wasn't about to renew it when I can host everything under my domain.
I seem to remember hearing that Go Nagai never actually visited the studio or had very little involvement in the production. He just designed everything. I don't know about the latter part but the former can't be true since he appeared in the Star Fleet Command set being interviewed in the Preview Show.
But I suspect from that, that he may not have any original artefact from the show to call his own.
I would love to know what Louis Elman had planned for his Star Fleet sequel. It may even be possible to obtain a draft of it or something but I'm a bit shy about contacting anyone having anything to do with the making of Star Fleet / X-Bomber.