If you are absolutely sure you have the saves for this exact game, do the following. Start a new game and make ANY saves in slots you need to open (as for Defenestration, first three slots are reserved for autosaves here, so if u have file4.rpgsave and file5.rpgsave, make any save in-game in slots 1 and 2). Then close the game, enter gamefolder/www/save and replace file4 and file5 here with your saves. When you run the game again, it will automatically rebuild the config file for saves and your saves will become availaible.
PS I see you are not new here on f95... So I'm sorry for explaining obvious things (obvious for experienced RPGM player). If you already done this, maybe you accidentally have the saves for another game or for very early build of this game.