"Buses and taxis are arriving from somewhere."
Translation:Valahonnan buszok és taxik érkeznek.
Because we are supposed to emphasize "buses and taxis", not "from somewhere". (Because arriving things ALWAYS arrive from somewhere). So, to be emphasized, "buszok és taxik" should be placed in front of the verb.
Is "Valahonnan buszok és taxik érkeznek" somehow a better way to say this than "Buszok és taxik érkeznek valahonnan"? Technically the subject is on the stressed position. I know that the verb in Hungarian likes to be at the end but in longer or more complex phrases it often tends to go before the adverbials. Does my version sound bad?
Your version is just as good as the one above. It is perfect. Yes, you are right, the subject is in the stressed position in both. So you have a choice here, perhaps a stylistic choice. Or a choice of what you want to say first, what should grab our attention.
I am not aware of the preference of the verb to be at the end of a sentence. It can be wherever it wants to be. But, since the preferred stressed position is in front of the verb, it sometimes ends up being the last word in the sentence.
Check this out, it might help: