"N64 and the Wii follow ups" => GX 2 on the Wii U has shader support based on GLSL.

C and C++ SDK relates to what languages are used to write the games, and what compilers are available on the devkit, as console game development started to move away from Assembly, not graphics APIs.

The 5th generation consoles was the last one where C++ compilers were still to be made part of the SDK, or available via third parties like CodePlay, all 6th generation consoles introduced C++ compilers in their devkits, including Nintendo.

I have not a made a single remark on how that influences the look of the game.