Files with EUF extension are Font Files. The Font Files subset has 109 various formats. The software for EUF files is Private Character Editor. It can be installed on Windows. Other programs support EUF file extension. To open EUF files tools are: EUF File Opener, EUF File Converter, EUF File Viewer, EUF File Editor.
When making new characters, Private Character Editor uses two files. One has extension EUF. They load and edit the character set. The program is stored in C:\Windows\System32\.
Below are tips to open EUF files. Also listed are programs supporting EUF. To open, double-click the file. If Windows does not recognize the extension, it asks to select an app. That means no default app is associated.
You may need to update the app you use to open EUF files. Only the latest version supports the format. Or scan the file for viruses with antivirus software. Then associate the extension to the software in Windows Registry.
Europa Universalis IV