All of the temple treasures can be obtained no matter when you go to get them. I usually leave them and get them when I get the airship. If you missed the bevelle one go to Zanarkand and solve the puzzle for the zanarkand treasure, then leave and go back in again and solve another puzzle. (How can you miss the treasure In bevelle? I have never got the knight lance and there is a chest that you open automatically and I have never had to do the extra zanarkand puzzle.)