Couldn't an adverb like this one be put to use in a more relevant sentence?
Because "Too, we have sweets" isn't grammatically correct, and "We have sweets too" doesn't convey quite the same thing as the provided translation.
Why isn't 'also' accepted in the place of 'furthermore' in the English translation?
"Too" could have a different meaning. For example "He has sweets. We have sweets, too!" Furthermore means in "addition to the things I have already said". For example, "Children, you should come to our house. We have a swimming pool- and furthermore, we have candy"! :) Hope that helps!
Would 'We also have candy!' not convey the same meaning? You know, plus/minus the exclamation mark.