Although the music for the "magic bells" in THE MAGIC FLUTE is usually played on a celesta today, such an instrument is a C19th invention, and couldn't have been what Mozart used. Nor, for HIP bands playing at a=415, is it a usable alternative.
Here's what one HIP band in Australia used:
http://www.smh.com.au/news/entertainment/arts/the-otherworldly-feeling-of-mozarts-magic/2009/07/28/1248546727515.htmlNB these instruments may not have been completely obscure. Charles Jennens, librettist of MESSIAH, wrote to his brother (in his famous "maggots in the head" letter) that Handel was keeping an instrument at home "called Tubalcain" that was a set of bells "operated by a keyboard in the manner of a clavecin, and with this cyclopedian instrument he intends to make poor Saul stark mad". (referring to the mad scene in the oratorio SAUL).
Stephen Storace evidently brought one back from Vienna with him (or somehow arranged for its importation - unless he came by one someone in London?), since he scores for the "carillon" in THE SIEGE OF BELGRADE (1791).