thank you for the reply!
You can read about JA5 at https://tempesta-tech.com/knowledge-base/Traffic-Filtering-b... .
But the thing is that the hashes were just inspired by the work of John Althouse and there is no any relation.
Unfortunately, we didn't realize what "JA" stands for at the time we were designing the feature. We will rename it https://github.com/tempesta-tech/tempesta/issues/2533 .
Sorry for the confusion.