It would be more normal in English to say fiancé, or husband-to-be. Future husband is not wrong, but to me sounds more like you are talking about someone you pernaps don't really know yet, and you are just describing your hopes rather than any firm commitments.
It could be the same in Swedish, there is a direct Swedish equivalent of ’fiancé(e)’ but that’s not what you’re supposed to translate here. ’Husband-to-be’ would perhaps work as a translation though.
In contemporary English (at least the variety I speak), "future husband" is something you would say comically in reference to an attractive man that isn't actually your actual fiancé. Could it be the same in Swedish? Or does it mean more like "soon to be husband" or "husband to be" in a more serious way?
Those meme-like expressions tend to travel very fast from English to Swedish these days, so while I don't think the majority of people would use the expression that way, I'm sure that some do.
The Swedish sentence only ever means "husband" in this case, but English doesn't really use "man" in that way so it's not an idiomatic translation.
it does not take "he is my soon to be husband", is it a weird sentence or just an incorrect translation?