The formula should read
word_cng = BCNT[10:2]+(BCNT | BCNT)
- BCNT field has 11 bits not 12
- the parenthesized OR should express that the last incomplete word - if present - has to be read too
The same in the analogous figure in the OTG_HS chapter. I did not check other RMs but I take for granted all these findings are transferred to all relevant RMs.