I ran the position throu Hachu, and it wasn't able to find a mate with the FEN you provided, even after the Kirin move. After
1. +Ah9 Mxh9 2. +Pi11 Rxi11 3. +Lh11 Gxh11 4. +Hd12 Nxd12 5. Oh10= Xxh10 6. Qxd12 +Vxd12 (I think this is right, please correct me if I am wrong),
Gote's +VM guards the d12-l4 diagonal preventing a mate from occuring, resulting in
7. Nf11 Ki12 8. Nxg11,g12 Kj12 9. Nxh11,h12 Kk11 10. Nxi11 Kl10 11. Nxk12 Kl9 12. Nxl11,k11 Kk8 13. Nxk10,j10 Kj7 14. Nxk9,l8 Ki6 15. Nk7 Kh5 (keeps the Lion away from the vital SM guarding the 9-rank) 16. Nj7 Kg6 17. Ni8 Kf7 (guards all possible checking squares that would result in mate, with help from the +VM and PH) 18. Nh7 Ke8 19. Nxg8 Kd9 20. Nf7 Kc10 21. Ne8 Kb11, after which no mate is possible.
However, if the +VM on d4 is replaced with a +RC, it works!
4+A1gk2f1/6s2+P1l/1+H1n4r1e1/5N3mp1/5xpO4/11+L/9Q2/12/3+a8/12/12/12 w - 0 1
My guess is there was a copying error when you went to copy the FEN code for B23. The new position results in
I ran the position throu Hachu, and it wasn't able to find a mate with the FEN you provided, even after the Kirin move. After
1. +Ah9 Mxh9 2. +Pi11 Rxi11 3. +Lh11 Gxh11 4. +Hd12 Nxd12 5. Oh10= Xxh10 6. Qxd12 +Vxd12 (I think this is right, please correct me if I am wrong),
Gote's +VM guards the d12-l4 diagonal preventing a mate from occuring, resulting in
7. Nf11 Ki12 8. Nxg11,g12 Kj12 9. Nxh11,h12 Kk11 10. Nxi11 Kl10 11. Nxk12 Kl9 12. Nxl11,k11 Kk8 13. Nxk10,j10 Kj7 14. Nxk9,l8 Ki6 15. Nk7 Kh5 (keeps the Lion away from the vital SM guarding the 9-rank) 16. Nj7 Kg6 17. Ni8 Kf7 (guards all possible checking squares that would result in mate, with help from the +VM and PH) 18. Nh7 Ke8 19. Nxg8 Kd9 20. Nf7 Kc10 21. Ne8 Kb11, after which no mate is possible.
However, if the +VM on d4 is replaced with a +RC, it works!
4+A1gk2f1/6s2+P1l/1+H1n4r1e1/5N3mp1/5xpO4/11+L/9Q2/12/3+a8/12/12/12 w - 0 1
My guess is there was a copying error when you went to copy the FEN code for B23. The new position results in
1. +Ah9 Mxh9 2. +Pi11 Rxi11 3. +Lh11 Gxh11 4. +Hd12 Nxd12 5. Oh10= Xxh10 6. Qxd12 +Axd12 7. Nf11 Ki12 8. Nxg11,g12 Kj12 9. Nxh11,h12 Kk11 10. Nxi11 Kl10 11. Nxk12 Kl9 12. Nxl11,k11 Kk8 13. Nxk10,j10 Kj7 14. Nxk9,l8 Ki6 15. Nk7 Kh7 16. Ni5 Kh8 17. Ni6 Kg9 18. Nh7 Kf10 19. Nxg8 Ke11 20. Nxh9,g9 Kd10 21. Ne8 Kc11 22. Nc9 Kc12 23. Nc10 mate.