TSAPI | TShock Scaffold API enables developers to build plugins | Frontend Utils library

.Net doesn't have the concept of 'global functions'. Everything must be contained in a class. The C++/CLI compiler will take some methods & variables that look like globals, and stick them as static members in a special class, but apparently not everything. Take the code where you're doing recognizer->SpeechRecognized += ..., stick it in a class (ref class, so it's a managed class), and put sre_SpeechRecognized in that class as well.

For the string assignment error, you need to move the assignment from the class definition into a constructor. Like C++, C++/CLI doesn't allow instance variables to be assigned in the class definition. However, I would consider leaving off the explicit assignment: Since you're assigning the empty string, consider just leaving the field as nullptr, which .Net ensures by default.