Well, I'm not going to argue with the manual.
I would stick with 14.6 x 4 = 58.4V bulk/boost/absorption
and 13.6 x 4 = 54.4V float.
At 58.4V, it's critical that NONE of the 12V batteries are over 15.0V - preferably, they're all at very nearly 14.6V.
If you didn't so so before you made 48V, you should individually charge the 12V to 14.6V.