Do you know how the pre-modern Old Norse speakers
treated unfamiliar objects? That is, when they
encountered something for the first time, did
they tend to create new names, or would they
adopt the names used by the people who
introduced them to the thing?

others can probably answer this better than I, but from botanical nomenclature it's amazing how many unrelated and sometimes dissimilar in appearance plants have the same name accross Europe and Scandinavia<G>..
Most not as famous as Yggdrasill<G>..
FriðR,
Pat.