Guild Wars 2

Some of the achievements in this category are worth some achievement points, but if you hover over them (for example, in “A Season of Merriment”), the number of achievement points shown is zero. See attachment.

So which of the two should I believe?

Well since you havent completed it one time yet its currently worth 0 points

Ooooh I see now, thanks for clarifying!

This has to be one of the most confusing pieces of UI ever though :/

In your screenshot, one window shows what the Achievement is worth when completing the task at hand (if you mouse over, you can see all possible tiers and points). The other window shows what you have achieved so far. The window with 0 will eventually show 10, then 20, then 30…up to 100 (max).

It would be odd if they showed the same amount.