If there still are some Nuendo only options used in the project, you could download the Nuendo trial and use that:
There is one vast difference between the Cubase and Nuendo trials. While the Cubase trial-license is based on a calender month, the Nuendo trial-license is based in working hours. 400 of them to be exact. So, if you use it sparingly and work quickly, it could last you quite some time.