However, the center of the Fornax cluster is one and a half degrees north. I think it's likely that Swift saw two of the galaxies there, but choosing two out of the 15-20 that he could have seen would be pure guesswork. Similarly, Lauberts's guess in ESO (ESO 358-G040) is based on a reliance on the 1 degree difference in declination more than it is on the likelihood that Swift actually saw the object: ESO 358-G040 has a total visual magnitude around 16.2, likely putting it beyond Swift's limit, especially given the far southern declination.
A third possibility is raised by Kreutz in a note following Swift's list in AN. Kreutz notes that the offset of Swift's position from that predicted for the comet by Finlay is 38 minutes east, and 4 degrees 1 arcminute south. However, searching at Finlay's place for a double nebula turned up nothing, either.
Other objects found by Swift on the same night include NGC 1797 and NGC 1799, both very near Swift's positions for them; and NGC 2589, like NGC 1392, not found at Swift's position (see Herbert Howe's note in MN 61, 29, 1900, copied into the IC2 Notes).
In the end, NGC 1392 is another of Swift's nebulae "not found."