Translator, compiler or interpreter?

Depends, act as compiler:

;Compile function on file load:
(= (f) 42)

;Compile function on file load:
!(add-atom &self (= (f) 42))

;Compile function when compilemyfunc gets called:
(= (compilemyfunc)
   (add-atom &self (= (f) 42)))

Act as interpreter:

;MeTTa code to Prolog goals, executing them directly (no clause assertion w. bytecode compilation)
(: myinterpreter (-> Expression %Undefined%))
(= (myinterpreter $code)
   (let $temp (println! ("Runtime-interpreting code" $code))
        (eval $code)))
   
!(myinterpreter (if (== 1 1) 42 43))
!(myinterpreter (if (== 1 2) 42 43))

Same translation pipeline ( https://github.com/patham9/PeTTa/blob/main/src/translator.pl ) translating from MeTTa to Prolog, but eval calls the resulting Prolog goals directly (technically compilation to Prolog still, there is no classical AST-walking eval loop of a traditional interpreter) while add-atom of a function asserts the translated clause which triggers clause indexing and compilation to bytecode.