Question about the lantern pieces in the Winter Toy shop set
I don't have this piece to check this assembly physically myself to confirm. However, the same design has passed TLG design review not once, but twice: first with 10199 set you mentioned in 2009 as well as 10249 six years later, which is updated version of 10199. So I'm rather confident there is no flaw.
Looking at the picture it seems like Cylinder Hemisphere 2 x 2 with Cutout sit underneath the round plate's ridge, thus making it stable.

I have built this assembly virtually. Here hemisphere is placed above  round plate's ridge intentionally, to show the fact that hole diameter is smaller. Thus, by placing hemisphere below round plate (as it is shown in instructions) will block it from moving vertically.