Is there any way to use the save editor in this game? I can change the value of my inventory but can't change the value of my character's talent nor stat.
YOu can safely edit your saves but you need to decompress the saves with "RPGmakerSaveEdit.exe" or "MySaveFile.exe", I don't remember which one I used as I have both files in my save folder. You decompress them to a .json file, edit it, then recompress. Editing the Json file is super easy, all you need is some sort of text editor that all modern PCs have, but I recommend you use something like "notepad++" so that it parses the lines out correctly and doesn't fubar the .json when you save it.
Don't do this if you're not sure what you're doing, or at least make backups of your saves. I got the above programs from this site somewhere. Up to you to find them.