Character does not convert in C#

Well, I'm virtually certain that it's an encoding problem but, unless the encoding was set specifically with VB.NET, then it's difficult to see why it wouldn't work in C# as well.

The default encoding for StreamWriter is UTF8 which can handle any unicode character.

However, BAULÉ looks like it might be a French name so I'd try Windows 1252:

var sw = new StreamWriter(filePath, Encoding.GetEncoding(1252));