We also have a higher level C API on top of Stream Engine that we use for games. It’s included in Tobii Unity SDK.
The name of the dll is Tobii.GameIntegration.dll. It also has a C# interop with the function signatures.
But we don’t recommend using it as public API and won’t provide any support.
So I would suggest to stick to Stream Engine API or use Tobii Core SDK and C#.