Other than superglue, epoxy putty is another solution that I hear from time to time. It *can* be fixed either way - i..e don't give up!
Figma sometimes suffer QC problem - I know some tend to break easily. Tsukasa (柊司/柊 つかさ) and Drossel are some of the examples for shoulder joints.
Otherwise, it may come down to handling problem. As hoying710大大 has mentioned, they're not as durable as 山口式. Joints must be handled carefully and held near the joints.
I think epoxy = 環氧樹脂. 混合畢地 works fine too by the way.
What warxv bigbig showed is called pinning as I've mentioned on my first post (first URL link). You should give it a try. It's one of the best and most stable method to fix joints.