Trying to find and bridge USART pins from the manual of an STM32 board
D6(PB10) to CN9 pin RX(D0)

Yes, alternatively you could connect CN10.25 to CN9.1 (RX, D0)

D10(PB11) to CN9 pin TX(D1)

No, D10 is PB6, not PB11. You need to connect CN10.18 to get PB11. CN10.18 to CN9.2 (TX, D1) is what you want