Liburnan Isis in Germania

Tacitus: Germania

9.2

"Pars Sueborum et Isidi sacrificat: unde causa et origo peregrino
sacro parum comperi nisi quod signum ipsum in modum liburnae
figuratum docet advectam religionem."

"Some of the Suebi also make sacrifices to Isis. Of where the cause
and origin of this foreign cult is, I have figured out very little,
except that her image, shaped in the Liburnan fashion(?)/in the
fashion of a Liburna(?) points to a religion coming from the
outside."

What is 'liburnae' here? My dictionary says: 'liburna' "light, fast-
sailing warship; (Liburian/Dalmatian/Croatian galley/brigantine)"
(Croatian??). This makes little sense (the goddess placed in a model
ship? Bronze age figurines once part of a model ship have been found
at Grevensvænge)? Liburnia, on the other hand, was the region made up
of Raetia and Vindelica.

Can anybody help me out here?

Normally when a Roman writer mentions that a Barbarian people
worships a Mediterranian god, one assumes that he is using
a "interpretatio Romana", and that the Barbarian god actually had
another name and no relation to the one the writer identifies him
with. But in this case Tacitus explicitly states that the cult is
foreign (the "Liburna" thing also points in that direction). I
suppose this means we can take him on his word, that this is actually
an Isis cult? Anyway, if a "native" Germanic goddess is meant here,
who is it?

And of course I shouldn't hide that I think this is another
indication that the story of the "Odin" migration is true. Note we
are talking about the Suebi here, the confederation of tribes which I
try to identify with Odin's first attempt at setting up a
confederation, based on his own people, in Saxland (Germania).

Torsten