I've seen a lot of TZn wedding invitations (from different parts of TZ) and I've never seen it spelled that way. Maybe in Kenya they spell it that way? Where is the author from?
I think the author's originally British but she's a university swahili teacher who's spent years in Tanzania... but just to be safe I'll be saying "harusi".
I only know arusi .... I am Kenya oriented... some consonants are difficult for some tribes ... the "h" is one of them. Then there are difficulties with the "v" "r" and even "k".