I understand that MFU reached a potential settlement on financial terms but was unable to recommend the deal because BA would not remove the loss of staff travel and loss of bonus from the agreement.
The information from MFU about current strikes references the right not to be punished for undertaking legal action. If correct, this is why many people believe that BA could have averted the current strike at very little cost.
As for knowing what one signed up for, anecdotal evidence suggests that MF crew are not earning what was advertised. I cannot confirm if that is the case, merely that it is what is suggested in answer to the question.