My take, BMS is usually treated as part of the finished battery.
Never heard of any fusing balance leads, usually max 3-4A current, 18AWG.
If I were pushing that, using balance leads for unattended "node charging" some do 8A supposedly, maybe? but I wouldn't, I pay attention charging any LI chemistry
a temp sensor cutting off the charger's input would be a better solution anyway.
Now the power pair is a different story, sure put a good quality over sized under rated fuse on the positive wire near the post
especially if the wiring is long and or exposed to shorting in an accident.
A master switch to isolate the pack for when messing around is a good idea too.
I do not trust CBs much, good ones at high amps cost the earth.
But all these extras also add resistance, complexity, more points of failure
so most people KISS and take their chances
