In STM32F446xC/E DS rev.6, Table 10. STM32F446xx pin and ball descriptions, SPDIF-Rx input pins are named SPDIFRX_IN0, SPDIFRX_IN1, SPDIFRX_IN2, SPDIFRX_IN3.
In the same DS, Table 11. Alternate function, the same pins are named SPDIF_RX0, SPDIF_RX1, SPDIF_RX2, SPDIF_RX3.
In RM0390 rev.3, in 27.3 SPDIFRX functional description, these pins are referred to as SPDIFRX_IN[4:1] and in Figure 337. SPDIFRX block diagram as SPDIFRX_IN, SPDIFRX_IN, ..., SPDIFRX_IN[n] where n=4.
In the same RM, 27.5.1 Control register (SPDIFRX_CR), INSEL bitfield description, these pins are named SPDIFRX_IN1, SPDIFRX_IN2, SPDIFRX_IN3, and SPDIFRX_IN4.
There are still no bitfield values defined in the CMSIS-mandated device header, so I can't comment on that (but wrote this deliberately to remind once again of my request for these values). I don't care about Cube and kin.
In other words, regardless of 3 different naming scheme, the DS numbers pins from 0, whereas RM from 1. That's very, very confusing.
Please, unify the pins names and numbering.