What does svirfnebli mean, and how is it different to svirfneblin?

A recent answer to a question has led me to obtain an e-book for The Dark Elf Trilogy, and the section I am reading uses the word svirfnebli as well as svirfneblin, but I am unsure if it is a printing issue (or possibly a scanning issue) or an actual word, and I can’t really tell why is it different from svirfneblin.

Examples:

When the svirfneblin guards ushered him in

Scores of svirfnebli rushed about their posts

Both seem to be referring to multiple deep gnomes, so I am unsure, but this is the first time I have read the word svirfnebli, and it is used multiple times in the short part of the book I have read so far. Does anyone know what it means and how it should be used?

If possible, I would like to know if the use of the words have changed through the editions, maybe in 3rd edition they both had a use and it was simplified for more recent editions?