I have been using Sparx EA for years. Mostly with Java, but a few years ago I used the round-trip feature for a C# project. It appears Sparx has changed the user interface and I cannot for the life of me find how to generate C# code. It keeps defaulting to Java.
I tried following their documentation but it may be a bit dated, as I didn't see the same options. So I poked around a bit. I found the Programming Languages Datatypes and selected C# for the product. That didn't work. I also tried Manage Project Options and set the Default Language for Code Generation to C# but that didn't work either.
What is the secret?
In EA each class has a code generation language feature you can change.
You can set the default language using the option
Configure | Model | Options | Source code Engineering
In order to change the code generation for classes in an an existing model, use the option
Develop | Preferences | Options | Reset Source Language
This answers has been written for the current version of EA (15.2). Menu locations might be different in v14, but the same options are available.