In the pit this year we have Britten's opera Turn of the Screw http://www.nzopera.com/2019-operas/the-turn-of-the-screw/ and a new ballet of Hansel and Gretel by Claire Cowan https://rnzb.org.nz/shows/hansel-gretel/ , both of which have small orchestras which include a harp. I haven't seen the Cowan part (possibly it doesn't even exist yet!) but she generally writes quite big harp parts so I'm guessing it will be notable.
There will be harp at the Auckland and Wellington shows, and likely ChCh as well. Will see if I can get confirmation for you.