Is a TXB0108 apt for level-shifting in SPI programming?
The TXB0108 requires the other devices to have a drive strength of a least 2 mA, but the W25Q64FW is specified for only 0.1 mA. And other auto-sensing level shifters have similar restrictions, so it is not possible to use the Dual/Quad SPI modes.

In normal SPI mode, you have three unidirectional signals to the flash, and one coming from it. This can be handled with a four-bit level shifter with individual direction controls, e.g., (SN)74AVC4T774; there's also the 74AVC4T3144 for this 3+1 combination.