1. Download old build : download_depot 665890 665893 7920408001856560739
2. Copy the build download from D:\Steam\steamapps\content\app_665890\depot_665893
3. Paste the build to D:\Steam\steamapps\common\Jay Fighter Remastered
4. *optional* for me this is how it worked. Delete mono then undo mono back from trash
5. Delete JFR Remastered.exe
6. JFR.Exe from D:\Steam\steamapps\common\Jay Fighter Remastered
7. Kill one enemy in game
8. Achievement pop

very simple and the only way I know to get the achievements.