Maybe like me you have a bunch of PS1 games of PAL region, that you have replaced with the often much better NTSC U/C versions? Then you should know that while the PS1 memory cards are region free and can contain save games of mixed regions, the savegames themselves have regional tags set on them so that savegames made by a different regional version of a game while always show up as generic "used block" as if it was created by any other game.
Fortunatelly, for plenty of PS1 games, it is possible to change the region of savegames.
It should NOT matter if the game is a "PSOne classic" from PSN or a physical game. It should not matter if the game is "Greatest hits"/"Platinum" or not etc.
It DOES matter if the game has any kind of in-game differences - if the game actually expect different data in the savegame, anything could happen, so keep a backup of the original savegame, as well as all other save games on the memory card. I play on PS3 so I have one virtual card for each game.
I have tried converting 4 games so far from PAL to NTSC (FF1, FF4, Medal of Honor, Breath of Fire IV), no problems so far.
I have no idea of the success rate converting to and from Japanese saves!
Also note that it is impossible to via PS1/2/3 browsers/memory card utilities see the difference between the different regionalities so try to keep them appart so you don't get them mixed up. These browsers will always concider saves of different regions as from different game, so they are always possible to have side-by-side but since their icons and names will not differ it might get confusing.
You will need a way to get savegames from and to a Windows PC - DexDrive, a PS2 that can run ULaunchElf or some Game Genie or such, the PS3 Memory Card adapter, USB stick, etc. Best option depends on your situation and available hardware.
* Download MemCardRex from: http://shendosoft.blogspot.se/ .
* Start the game of the "target" region. Create a dummy save on an empty memory card. Many games have virtual "slots", if possible you should create saves in the same "slot" as your real save game.
* Use any method to copy both the original save games as well as the dummy save games to and from a Windows PC.
* In MemCardRex, select Edit -> "Import save". Open the dummy save.
* Right click on the imported save, and click "Edit save header".
* Note all of the values. SCxS-yyyyy is the product name under which the game was sold as in the region. "x" is E for Europe (PAL), U for NTSC U/C, P for NTSC Japan. yyyyy is a five digit number, each games number is different for every region. Also note the Identifier, which is a string the game use to separate its own games. A few games contain region in this string as well (for example Breath of Fire 4 has "BOF4xxyy" where xx is the "slot" (00-14) and yy is the region (US for US, PL for PAL, unknown for Japan).
* Now import the original save, and select Edit save header, and change the SCxx-xxxxx, the region dropdown, and if needed, the regional code in the ID.
* Right-click and select "Export save". Select an appropriate format. Since the product code (SCxx-xxxxx) is a part of the file names, it is normal that the exported file has a different file name than the original one.
* Move the modified game to your memory card.
* In PS1/2/3 interface, save has garbled graphics and/or text - the save file is completely invalid. Check which format you exported the save from in MemCardRex, and check how you copied it to your PS1 memory card.
* Save looks fine in PS1/2/3 interface, but game only shows save as a block used by another game: Check that all the regional parameters were changed to the values corresponding with the "target" region.
* Save looks fine in PS1/2/3 interface, but game crashes or glitches when reading the memory card, when loading a savegame, or later during gameplay. Or, there are items missing in inventory, you are on the wrong level or in the wrong state - the save is probably not compatible with the new region.
Hope this was of use to anyone!