unfilled pronote was wrongly filled-in by the money lender

Changing the year amounts to material alteration and the promissory note is invalid.

But such a defence of material alteration should have been specifically pleaded in the written statement filed by you.  You cannot take this defence at a later stage.  A money lender can fill the amount in an unfilled pronote.

But as your counsel has signed the compromise, you can validly challenge the compromise order.  But in front of the judge when the compromise was entered into, you had been a silent spectator is not correct.  You should have protested immediately.  Anyhow it is not too late, engage a new counsel and challenge the compromise arrangement and also file an application for amending your pleadings to include the defence of material alteration and contest the case.  

The undertaking on the part of your counsel shall be treated as of you and you cannot chellenge the validity of pronote once you have accepted a liability out of this.