Interesting how all the multisample visuals and configs are non-conformant.
Try to match the attributes more closely:
SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 8); // or 0 if you don't need it.
Do not set SDL_GL_ACCELERATED_VISUAL to anything above -1 or, I think, it will not consider the non-conformant ones.
It looks like it uses the GLX route. Perhaps you have more success with EGL. Set the SDL_OPENGL_ES_DRIVER environment variable to 1 and check if anything changes. I’m not that familiar with the X11 code in SDL, this may not do anything.