Here’s a minimal repair: choose the path A2→A12 A4 A3 and A3→A10 A13 A5 A8, then insert exactly the missing terminals into the existing RHS’s so that each block matches the target. 

Updated production rules:
rule_9:  A6  -> 9 16 15 14 13 12 11 10  
rule_10: A7  -> 17 24 23 22 21 20 19 18  
rule_12: A9  -> 33 40 39 38 37 36 35 34  
rule_14: A11 -> 41 48 47 46 45 44 43 42  
rule_15: A12 -> 49 8 7 6 5 4 3 2  
rule_16: A13 -> 50 32 31 30 29 28 27 26