Strange New Worlds books weren't the only ones to have short stories in them. There was one other book that had several Next Generation short stories in them. Most of them were pre-Nemesis, and a few weren't. In one of them about Wesley Crusher, they had Spock dying, Picard dying of dehydration, and Wesley being a married man. It turned out to have the traveler in it. How were they able to get away with such dramatic changes? Is the traveler some sort of time traveling alien who can change history or something?First off, none of the books are canon, and they never have been so you are not going to get any canon recurrection, unless the new movie does it. As for short stories with the Borg, I'm pretty sure there were several Borg stories in the Strange New Worlds collections. It's not a short story, but one of the novellas in Seven Deadly Sins focuses on the Borg. It sounds like you're thinking of the fan series Renegades.
God bless, Jason Irelan