I'm not sure what I made fits in the category so I'll just leave it here.
A few month ago after I had tried making SFS work with UE4 I came to the conclusion it just wouldn't work out of the box, UE4 doesn't allow RTTI while SFS client API needs it to function.
To get around this limitation I wrote a full plugin for UE4 as means of implementation of the SFS API, as it stands, it needs much further testing but I've successfully logged in from a game instance. I would say around 80-90% of the API functionality is working (there's still some work to do on it but those are not atm priorities for me). To note one of the huge problems is that boost libraries can not be used inside of the UE4 project so it is all working through Interfaces.
Also I'm not a specially experienced C++ developer so excuse me for any less than optimal code, it is released under MIT License so feel free to use it and if interested contribute.
Project page: https://gitlab.com/FlyingCookiePublic/SFSPlugin
p.s. I'll add some instructions on how to make it work, hopefully till the next week