According to this page, the following types of characters are allowed in names:
So that's hiragana, katakana, extension, and repetition marks. Valid examples are given for each in the parentheses.
The following character types are not permitted for use in names:
It says that roman characters, as well as non-standard kanji, Arabic and Roman numerals, and some other unusual characters (shapes, etc. that might be included in the unicode standard, I assume) are not acceptable for registered names.
So there you have it. Assuming this source is to be trusted then we can conclude that Japanese names are registered with Japanese text only. Foreign names, as in the examples above, will need to be given at least a katakana equivalence.