> How would you translate “well fed raven” or “fat raven”?

I suggest "saddr hrafn" or "saðr hrafn"
as in Rögnvaldr's poem:

"Golli Gautrekr þótti
góðr illr kyni þjóðar,
saddr varð svanr, en hræddisk
seint, skjótt, konungr, Þróttar."

Kveðja,
Haukur