Step E7+5 may not be best move but shld not lost that easily.
At that time red thinking is need to move R9=7 when black R4=3 and potentially have H7-6 .

Whether black exchange or not , red should be better as black R1 not yet making it move.


But once after that move (H7-6),red already felt that is a very diffcult game.

不明白。