Since you mentioned creating a C# program to do this, you can achieve that using the LEADTOOLS Multimedia SDK (Disclaimer: I work for the SDK’s vendor).
The SDK contains audio processing filters that can be used during playback, recording or modifying existing audio/video files. In particular, the following 2 filters might be what you need:
First insert the ...
Microsoft Visual Studio Code is the one!
As per your requests:
it supports multi documents and tabs
performs indentation and keyword colouring
has a number of extensions/add-ons which can really enhancing your programming experience
supports RTL Languages in such a way that languages such as Arabic or Hebrew can be used to name classes, functions, variables,...