Is it not the case that a company is obligated to educate the crews in the legal constraints of FTL's. It is the individual's responsibility not to accept a duty outside the limits. "Only obeying orders." will not be a defence of violation.
When called out from home, 'asking the pilots' is not an option.
I have not worked for an airline where cabin staff understood how to calculate the FTL's. (Perhaps the well unionised majors would be an exception.) The company gives the C/A's the rules and expects them to self-educate. Not the same thing IMHO.
Now you come to real chestnut; and even the senior crewing and rostering officers couldn't work these out sometimes, and when the manure hit the air conditioning they didn't bother to try, just call out the crews.
Duty limits when called from SBY?
One where you can get into a real slanging match with crewing because neither party knows the rules.