I don’t really have a problem with it, but what’s the deal ?
Our build tool that is used for compiling the Engine and all projects is currently written in C#. The files you are seeing in your projects are so called module rules and target rules. They provide settings and details for your module so that Unreal Build Tool (UBT) can build your module correctly. If you are a programmer, you should definitely take a look at them - they are pretty easy to understand.
By the way j3rkey, I found your build system to be quite clever. Not sure who came up with it, but nice job.
Alright, Thanks !