The Mozilla Public License v2 is clear about the licensing of modified versions: If you make modifications to a work covered by the MPL, the modified work must remain licensed under the MPL.
The difficulty is in the determination whether a ported version should be regarded as a modified version (and thus required to be licensed under the MPL) or a new work that is (loosely) based upon the original (which means you would be free to choose your license). That determination can only reliably be made by a lawyer, which I am not.
As you state that most of the translation was done by an automated process, chances are that your .NET version will be seen as a modified version of the original.
Your best options are either to stick with the Mozilla Public License, or to contact the authors/maintainers of the original and ask them if they agree to using a different license for your port.