No, as I linked to, this is an existing project. I have no interest in altering the original source code. I'm an experienced C# programmer, but have very little experience with C. I believe that I would be able to compile the Tilengine source code for different platforms, but there's no chance of me making significant alterations.
What I'm interested in is making a more fleshed-out C# binding, that makes it easier to embed and use Tilengine in modern engines, and approach development in Tilengine in a more object-oriented approach, consistent with typical development in C#. The C# binding created by the original developer seems to be a little on the automated side. And all it really does is translate the original code into C# structs. In order to use that binding, you basically have to code the same way you did in C, only in C# instead. That C# binding also treats the engine instance as a static singleton, preventing you from using multiple instances in the same application.
Trying to cook up a "true" retro 2D solution can be a challenge in modern systems. You have to specifically tweak your mip-maps and point-clamping. You have to use a RenderTarget for post-process scaling. You have to cook up multiple custom shaders in order to implement a limited form of color palette support. You have to worry about polygons shifting to sub-pixel values. With Tilengine, all of that is just part of the system. It's the default approach. No extra effort, tweaking, or coding is needed. Every displayable graphical element in Tilengine has a color palette, and can have that color palette altered freely. It's not something special that you have to implement, it's built into the core engine. Tiled tilemap support doesn't require a separate library or plug-in, and you don't have to worry about performance, or map size, or how many quads or vertex buffers are going to be fed into the GPU. All that is built-in, and can be loaded with a single line of code.
Is it for everyone? Clearly not. There's tons that you CAN'T do, and probably shouldn't try to do in Tilengine. Tilengine does 2D scan-line rendering ONLY. While you can simulate Mode 7 in Tilengine, true 3D rendering is a waste of time. It is very much geared toward classic, 2D, tile-based sprite games. If that's your jam, it's worth taking a look at. But given the number of popular and capable 2D, retro sprite-based games that I've seen produced using Monogame, I thought that perhaps someone around this community might be interested in such a project. It could be that I was wrong. My initial push for this porting project was for Unity, anyway, and that effort is still moving forward. I can probably save some time by not bothering to make it available for Monogame as well.