Both parties are responsible for community debt. The court-ordered debt division is between you, your ex, and the court only. Creditors do not have to follow it. If your ex does not pay the debts the court ordered them to pay, the creditor can come after you.
Think of it this way: Your cousins Amy and Beth are starting a business. You lend them $100.
Each signs a written note, to you, to be liable for the full $100. Each cousin alone should be good for about $50.
A few months later, Beth decides to leave the business. Amy says she will keep all the business’ assets and debts (including the loan to you). Beth agrees.
You ask Amy for the $100 she owes you. Amy says she cannot pay you.
You ask Beth to repay the $100. Beth says, “I am not responsible for that money. Amy and I agreed she would take the debt.”
An agreement you had no part in has now limited your ability to collect your $100! This is unfair. Both Amy and Beth agreed to repay you. You never agreed to anything different.
This shows why the law does not change the creditor’s rights when there is a divorce. Like Beth, the divorcing parties cannot change the rights of creditors by their agreement with each other.
The divorce decree’s debt division has some value. If your ex does not pay, you can sue your ex for damages (money) and contempt.