If you can not build an "ADD-ON" that is compatible, please don't build the "ADD-ON". Or maybe changing email clients is better?

I am very surprised that Thunderbird Ver. 78+ still is limping along with few enhancements. It seems to me that if the program can import then including export is not far from the pond. As most know, one has limited ways to save important data from TB. The old Import/export ADD-ON was excellent in providing a way to protect one’s data in TB. Why can’t the TB team provide a way for ADD-ON programmers to update their ADD-ONs without any issues?
Please, Pretty Please, Pretty Please with your favorite food. Consider it.

IET NG for TB 78: