I'm biased for sure, but I definitely have that gut feeling. I mean, for me, it could really have been spelled based on pronounciation, but the way *they* would pronounce a Belgian word with an English accent, back in 96-97.
The word may have had its structure a bit damaged/changed that way in the translation to Japanese process, that's very possible. It's not like we're translating the work of persons of letters.
cu - bir / ber - duns / dons (from initial plural form), is really how they could have pronounced it, and it definitely rings the bell of good sense in my book.
There's too much resemblance and several hints pointing towards it.
Sure there may be a more correct Japanese spelling for the word "cuberdon", but here we are talking about French, English, Belgian and Japanese, in 1997.. it's no surprise if the word has quirks.
But it doesn't have to cover up what, to me, is almost obviousness.