While English is widely used in Vienna, all official documents should be translated into German by a sworn translator.
Please note that even if some offices accept an English translation of documents, that is rather the exception, not the rule.
Another thing to consider is whether there is bilateral agreement between the country that issued the document and Austria for recognizing official documents without the need of a legalization and an apostille. If you are not sure whether there is an agreement or not, get in touch with your embassy and ask!
You can search for sworn translators using the languages you need as the search criteria here: https://www.universitas.org/en/home/.