Question

how did jumman and alagu maintain their role as a judge?

Answer 1

when Algu was chosen judge he understood the duty of of a Panch and kept his friendship aside and gave right verdict.
Soon, Jumman also got a chance to become judge in dispute of Algu , he had a great chance to take revenge from Algu by giving verdict against him but Jumman, when sat on seat of the Panch , realised that voice of Panch is voice of God and he did justice and gave correct verdict.
They became friends again and Jumman realised his mistake and learnt a very important lesson lesson.

Answer 2

When Algu was the jugde he maintained his role by giving justice to Jumman's aunt who was in the right.

After Algu had taken Jumman's aunt's side, Jumman was very angry with Algu.
And wanted his revenge.

When Jumman was the judge he maintained his role by not taking his revenge and giving justice to Algu.