[hnarn]

Swedish has a long history of importing words from French (as do many other European languages for obvious historical reasons), so I’m quite sure this is indeed the origin of the word.

What usually happened though was that after importing the word, it (sometimes) got a new spelling more compatible with Swedish phonetics. Other examples of this include Swedish “trottoar” (fr: “trottoir”)

[cozzyd]

I guess it's obvious in retrospect but I didn't realize that the Romanian trotuar is also an obvious French import.

[hnarn]

A lot of Swedish words that end in -oar (like “reservoar”, “memoar” etc) are all french import originally ending in -oir, so if you start digging into words ending with -uar in Romanian you’ll probably find more :-)