Hofner have always used hide glue in the neck joint, and still do.
Hide glue is very thin and very strong - it holds upright bass necks, and the string pull is more than twice that of a bass guitar.
The advantage of hide glue, and the reason it is used in violin family instruments, is that it is not permanent - it comes apart with heat. So in a way it's like a bolt-on neck - you can always remove the neck without damage to the joint surfaces, do whatever you need to do - like change the neck angle - and re-glue it into place. Once it's done by a pro (preferably violin makers), the bass is good for another 30-40 years.
I don't recommend using anything but hide glue on Hofner set-necks. With other glues you can still sometimes be able to remove the neck, I've seen it done, but there will be damage to the neck joint and a lot more work will need to be done to re-glue it - with hide glue.