"He has come now."
Translation:Han har kommit nu.
It would be correct and perfectly normal usage. However, as Zmrzlina pointed out, it would not be the most literal translation, but rather a translation of "Now he has come."
Apart from these two, no other word orders would be normal, unless you are writing strange poetry, in which case you might get away with "Kommit har han nu" or "Nu han kommit har" or even "Nu kommit han har" or "Nu han har kommit". In this imaginary poem, all of these options would probably be followed by a secondary clause, a rhyme, or some sort of continuation, without which they would sound really off.
No, where the word order corresponds well between the languages, we try to keep it that way.