It's a bug. I guess it's an old save that isn't working anymore. Sadly happens quite often with Renpy.
That one is serious. The default entry points should always work. I'll take a look.
edit:
Shad0wB If you use the default ending, Korra and Jinora wedding is canon. You can watch it in the mansion after you did some progress in the epilogue.
gb2
You don't have to engrave the ring to progress. Just do every sex scene once and you can talk to Katara. (You also could fuck the elder council and get your 25 bucks this way.)
I tested with the bughunt version though.