How many yolks and last direction mentions "flower" how much. Also picture has something mixed into the frosting. what is it?

In the one comment, the reviewer used 4 egg yolks with good results,

As far as the flower, I think that’s a mis-type. I’m thinking you add the sugar slowly as you beat the cream, and then mix in the vanilla.

Perhaps the author of the recipe will make some much-needed edits to the recipe.