Hi Chris~
A one dilution change doesn't mean anything. So, a drop from 1:640 to 1:320 is not significant, meaning you can't tell if that is a true change or not. Give it more time, and see what happens. The B3 has dropped a decent amount. B4 hasn't changed, but I wouldn't be surprised if she has been treating just 3 months.
In my case, my titers after 13 months of treatment went: B3 1:320 to <1:10 B4 >=1:640 to 1:40 B5 1:160 to 1:40.
Treat her longer....see how her titers change (or don't), and most importantly, see how she feels. Good luck and best wishes for a full return to health.
Best, Timaca