I've waited for a few days to try my pineapple tarts again. Pauline mentioned that the tarts will taste better after a few days when the jam finally "integrate" with the pastry. They do taste better than when I first bake them, but still no "melt-in-the-mouth" feel.
I've used up the remaining pastry and most of the jam in my fridge on Thursday. Made the second batch to bring to my in-laws tomorrow. This time round I bake them a little more golden (since I know they'll probably soften after a few days).
I'm still in search for a real melt-in-the-mouth pastry. I'll probably have to wait till next year as I won't be making any more pineapple tarts this CNY.