To be honest, in almost all cases, I am asked to do complete ports of games. Publishers/developers are usually looking for a quick solution to get their game on another platform, and I can do that with comparatively less time/cost than others.
That also means it's only been necessary to license Chowdren to very few developers. Every game is different, so I feel the cost is something that can be discussed on a project-to-project basis.
In terms of features, it's difficult to show you what's working/not working without going open-source
Chowdren was originally open-source in 2012, but in the end, that was simply not worth it.
However, if you check the list of supported plugins/behaviors/ACEs in the original post, that should give you a good idea of what is supported. That list only shows the Construct 2-specific features that are supported.