No, you're right, FHE is the ICAO code for Hello.
It's just that Iceland Express don't have any aircraft of their own, and Hello performs all their flights for them. On the nose of the aircraft you can see a small sticker "Operated by Hello".
'HUAF 619' landed at 1755lt, a Hongarian An-26. Its STD is 2130lt (credit: EWAS), but quite often requests are put in for modification of the STD (mostly for earlier departures).
Serial should be 407, but this needs visual confirmation. Edit: 407 visually confirmed, and still parked at apron East at 2145lt. Not a lot movement going on and propellors suspiciously alined...so maybe turning into a nightstopper?