No, it is not possible for the neutral on the shared split phase to ever see more than 54AI have my LV6548's in split phase operation (US) I am using a 60a 2p breaker from my main panel to feed them. The only worry I have is with the shared neutral. Each inverter can output 54a so there is a potential to draw 108a total. Not likely that the unbalanced load (neutral) will ever see that, but in theory it is possible. Breakers are common trip so if either leg draws over 60 amps the 2 pole should trip. I still am running tests on my system, I but don't like the fact that the neutral is shared between the inverters without being able to accept wire sizing for 100a or a double neutral.
Just my thoughts
180 out of phase means the neutral is always balanced to any output from either or both inverter.
Only way for it to draw higher is if they were both outputting on the same cycle.