@nadifb I am scratching my head here also. I tried adding that last name just in case the error somehow was addressing the 'family name' (I know in Korea, for instance, what we in America call the 'last name' is there called the 'family name' and it comes first. So if my 'family name was 'Kim', you would call me Kim Sheri). Anyway, that theory was shot since I just tried adding Alsina both as the last name of each of them and in the household name. (see attached screenshots).
If I were you I would try to delete that version of the household from your library and try re-saving the household to the library, then from there sharing them to the gallery. Perhaps they got glitched or something in the library or gallery. I cannot know.
I am perplexed by your saying that someone added a hashtag to your description while it was in the gallery. The only thing someone can do there is fav it, download it, comment on it, or flag it. Flagging would be bad, but if it was flagged I can't see how that would a call a name disallowed that is not. And none of these possibilities would add a hashtag to you description. Only you can add a hashtag to your description. Are you the original creator of the household? Anyway, I am puzzled also. Sorry I don't have a happier answer for your frustrations.
What language are you playing in?