OK, it's a bug in the grammar.

>> with ( t as TForm ).Canvas do ;

Quick fix: In line

>variable_list
>        : variable_reference {}  /* acessing func.recordfield not allowed here;as well as UNITNAMEID */
>        | variable_list {} COMMA {} variable_reference {}
>        ;

replace all 'variable_reference' by 'expr' so that it looks like 

>variable_list
>        : expr {}  /* acessing func.recordfield not allowed here;as well as UNITNAMEID */
>        | variable_list {} COMMA {} expr {}
>        ;