There is a somewhat-working SDL1.2 Glk out there, I managed to get it to compile on Ubuntu 16.04/16.10 x84! It’s called ‘nanoglk’. https://intfiction.org/t/new-glk-implementation-nanoglk-based-on-sdl/3641/1
I put the source code up on github.com/BroadcastGames/nanoglk with my hacked up Makefile I needed to get it to build on Ubuntu 16.10.
Finish this up for SDL1.2 and then making a conversion to SDL2 could be an option?