First of all, if your uncle can't repay the mortgage on time, the bank may recover the loan from you. If you can't bear the repayment responsibility, your credit record may be affected, and you may even be investigated for legal responsibility.
Secondly, if your uncle dies unfortunately and you don't go through the relevant inheritance procedures in time, the house may be frozen or there will be ownership disputes, which will bring trouble and losses to you and other family members.
Therefore, I suggest that when you consider accepting your uncle's house purchase, you should seriously consider all kinds of risks and possible problems, and you can consult a lawyer or real estate professional to ensure that your rights and interests are fully protected.