Svenさんは、らいしゅう　"なにで"　ぎんこうに　いきますか。 If you are supposing that Sven is going to use some kind of transit (taxi, train, bus..etc) to the bank, this sentence works. なんで= why なにで= by which (transit) どうやって＝how

Are you asking transportation to a bank? Perhaps it's better to use ”どうやって” instead of "なんで" if that is the case, because "なんで" is ambiguous here and sounds like you are asking a reason for going to a bank.

Hi! I think better you say なぜ instead of なんで。　なんで is informal. Svenさんは、らいしゅう　なぜ ぎんこうに　いくのですか。 this might be what you want to say, I think. ???