All that rain can’t be good for the ripening of the durians
They love it, if you don't give em plenty of water they need the water from the rain, it's not a "single" monsoon climate plant with distinct dry/wet season needs, Sarawak for instance have two monsoons "The northeast monsoon, usually between November and February, brings heavy rain, while the southwest monsoon from June to October is usually milder."
Some people (local farmers) who think less rain is better, water their durians in the dry and so they are proving themselves wrong, they will also add some during the summer monsoon.
Also have a look at the average rainy days throughout the year where d. zib is naturalized. D. Zib needs lots of rain and that spread out over the year.
As an example: average rainfall in Sarawak is 3,300 millimetres and 4,600 millimetres,
https://sarawak.gov.my/web/home/article_view/159/176/so no issue at all with ripening of the fruit. Poor management, insects etc causes issue with the fruit.