Does a non terminal token need an explicit definition?

Question

I am writing code in bison that parses various assembly instruction. Here is a tidbit:

text
    : text NEWLINE Instruction
    | Instruction
    ;

Instruction
    : r-type
    {
        instruction.format = IF_R;
        instruction.opcode = 0b0110011;
    }
    ;

r-type
    : add
    {
        instruction.funct3 = 0x0;
        instruction.funct7 = 0x00;
    }
    ;

add
    : ADD REGISTER COMMA REGISTER COMMA REGISTER
    {
        instruction.rd = $2;
        instruction.rs1 = $4;
        instruction.rs2 = $6;
    }
    ;

Assume that instruction (lowercase) is a struct, and the (ALL CAPS) tokens are received from a lexer.

Does the 'add' non-terminal need to have a grammar rule that says $$ = *something*; or is this set up fine. Also is it fine to have multiple semantic rules along the token chain?

I have tried getting help from AI. It says that the non-terminal nodes are not defined. and the way that I write my semantic tokens is not standard. the rest of it is nonsense jargon.