Retains its original name after taming. Svarnos is underground in the D-Block cells, which are accessible from a structure to the south-west of Ironclad Garrison. D-Block isn't always open (and is always closed during battles) so you may have to be patient.
Level scaling: Most NPCs will scale with the Hunter's level, within the constraints of their level range. Hunters can tame regular NPCs up to 2 levels higher than them, but can only tame elite NPCs of the hunter's level or below.