Is there a Synchronous CFI (Common Flash Interface) controller to NIOS II?

Rather confusingly that support solution talks about a core that no longer seems to exist.

For flash memories, the core to use is called the "Altera Generic Tri-State Controller" (located in Qsys under "Qsys Interconnect/Tri-State Components/Generic Tri-State Controller"). This core allows you to specify many parameters about what is being interface with, which includes a preset for "flash memory interface (CFI)" that you can use as a starting point. You will need to configure the various signal timing requirements for your flash (read/write wait time, setup time, etc.) information for which will be in the datasheet of your flash.

Once you instantiate a tri-state controller, you connect its Avalon-MM slave interface up to Nios, and export the tristate conduit to connect to your flash. If you select the CFI preset, you will see under the heading "module assignments" that there is an embeddedsw command to instantiate a HAL driver for CFI flash. This will be added to your design when you use the BSP settings file generated when you export your Qsys system.