I think it would be good if aliases had types, so that we could specify what the string actually represents.
"Localised name" might work for the primary name in other languages/countries/scripts.
"Search hint" would be good for marking typos, misencodings, etc as not being proper aliases, so that anything wanting to use the data for something other than searching could exclude them.
The main reason I would like them though is for localised sortnames. At the moment we can only specify one sortname, but there isn't one single way to sort things (in particular, other scripts usually sort things completely differently), so even though in NGS we can find out what an artist's name is in another language, we don't know what the sortname would be for that language.
It could also be used for things like birth names, full names or whatever (since it's normal for people to shorten their first name or leave out their middle name), although if it that one's added, how exactly it would work with performance names would need discussing.