I have to disagree with the idea that 22.5 is its own category. 22.5 is titled References Without Syllabification or Pronunciation and subsequent subsections discuss only definitions. 22.4 is specific to Indexes and it discusses ONLY indexes. The fact remains that there is no provision for two spaces following an index entry. If some extreme situation presented itself that made it necessary, it would obviously have to be addressed. However, this is not such a situation.
The number in both entries is clearly a year, as you identified it, and not a page number. The context makes this obvious to the print reader and the braille reader will get that as well, by reading the surrounding text. These entries should be brailled as the other index entries.