This file was developed while playing the PSP version of the game, however I believe all versions must be very similar. As far as I know the only missable in the game are the Scoundrel enemy drops (No. 36), which after you finish the 3 places where he appears, he cannot be found again. Just be sure to get both drops before you finish those areas.
Other potential missables are startup equipment and skills, if you want to have a perfect file never get rid of them. This is the same case as weapons/armors/accessories(some) found in treasure chests.
I believe MSG Commander will be using the file to create Tables that adhere to this site formatting.
Also, sorry for any typos in the file, English is not my primary language. In any case, let me know any comments/corrections/suggestions.