Even when it identifies the specific project, it doesn't know C#. I took some scans of some notable CMS websites (so the programming language is provably correct).
WordPress.org (PHP, correctly identified language and framework): https://radar.cloudflare.com/scan/88fcab24-5e27-4c77-8ace-94...
Orchard Core (C#, Modern .Net, correctly identified framework): https://radar.cloudflare.com/scan/88adbf69-c010-4074-a80f-03...
DotNetNuke (C#, .Net Framework, correctly identified framework): https://radar.cloudflare.com/scan/7889b8b9-4fed-43b6-8506-49...
Yeah, it doesn't detect C# for some reason and for some of our own sites, it even failed to detect that those were built with .NET (as we intended;)).