Do I have to change the tense of the verbs, more precisely add a "had", for this particular case of conversion from direct to reported speech?
Direct speech:
The witness: "I congratulate my good friend for the good demonstration he made just as I left for my car."
Reported speech:
He congratulated his good friend for the good demonstration he (had) made just as the witness (had) left for his car.
UPDATE
My confusion is like this. It appears to me that in the first case "he did" must change to "he had done" while in the second situation both verbs "did" and "left" have to keep their simple past form.
1) A simplified case:
DIRECT, The witness: "I congratulate my friend for the demonstration he did."
REPORTED: In that letter, the witness congratulated his friend for the demonstration he had done.
2) A more complicated situation:
DIRECT, The witness: "I congratulate my friend for the demonstration he did just as (when) I left for my car."
REPORTED: In that letter, the witness congratulated his friend for the demonstration he did just as (when) the witness left for his car.
or
REPORTED: In that letter, the witness congratulated his friend for the demonstration he had done just as (when) the witness had left for his car.