Thanks to my friend I found what was wrong.
- Unpacked pyparsing package had to be placed in the Debug folder of C# app in a folder named Lib. (I suppose it also could be in folder with another name, but this was faster for me.)
- Thanks to this page I also realized that I need to add some lines of code into the C# app.
So now it's:
string ExecutePythonScript(string path, string text)
{
ScriptEngine engine = Python.CreateEngine();
ScriptScope scope = engine.CreateScope();
ICollection<string> Paths = engine.GetSearchPaths();
Paths.Add(".");
Paths.Add("D:\\DevTools\\IronPython 2.7\\Lib");
Paths.Add("D:\\DevTools\\IronPython 2.7\\DLLs");
Paths.Add("D:\\DevTools\\IronPython 2.7");
Paths.Add("D:\\DevTools\\IronPython 2.7\\lib\\site-packages");
engine.SetSearchPaths(Paths);
scope.SetVariable("text", text);
engine.ExecuteFile(path, scope);
(...)
And it's at least not creating that Exception.