I have recently played a few sessions of 3rd ed. Our SG informed me he was able to rapidly generate our covenant library with a few die rolls. It seems the streamlined approach of a single score per art makes this area of covenant generation incredibly quick compared to 5th edition where you have to assign a level and quality for every summa and a quality for every tractatus for every art and ability.
Looking at the covenant rules a little more, if you wish to quickly generate a covenant of the appropriate season 3rd is very fast. It's much simpler than 5th, where between build point allocation and the colossal number of boons and hooks available in the Covenants book you can suffer choice paralysis.
Of course covenant generation is quick in 3ed. It is not proper chargen at all; very little detail is discussed, and does it even encourage a backstory? For the game that promotes the covenant as a character, and the most important character of the game, that's just weird. And that is true. Our longest running saga soon has only two of the original characters left; one magus and the covenant. Some players have changed, true, but several long-playing players have changed their characters too. Nobody suggests retiring the covenant.
The big problem with 5ed libraries is not the generation, but the maintenance over time, when the library grows. Making a score or two of titles for the starting covenant is not that much, but when books have to be copied at different crafts levels, and traded and sold and bought, and the list grows into the hundreds, then it becomes a chore without character and flavour.
We did get backstory for the Covenant, back when we used ArM3.
I don' recall it as being significantly less supportive of such than ArM5, tbh.