Whether High Court can determine a issue which has not been determined by the Tribunal

Yes. The High Court may determine any issue which has not been determined by the Appellate Tribunal. Further, High Court may also determine any issue which has been wrongly determined by the Appellate Tribunal, by reason of a decision on such question of law.

(ICAI FAQ PUBLICATIONS 06-09-2017 APPEALS TO HIGH COURT: FAQ NO. 60)