You can find it and many other hacking info in this uploader, https://ux.getuploader.com/FEkaizouwww
I believe you want this file specifically,
FE4 ツール、資料系.zip
Here is the map editor from that archive (download is only valid for 14 days), but I included two missing dll files. If that concerns you, grab it from the original source above. https://www.mediafire.com/file/ejmikom76j91j51/FE4MAPv8.rar/file
Hope this helps.