When one tries not to break ones promise, and to live life according to the well-being of others, this is a high concept of moral. Those concepts are not part of Buddhism directly, but they are derived from the inner Philosophy of mind and world. While they are certainly part of the discourses of Buddhist traditions, it should be important to notice that in Buddhism there is no doctrine -- this is if one looks at Buddhism as philosophy (close to the Pali Canon or the Theravada tradition).
What is Buddhist moral according to Buddhist philosophy then?
In Buddhist philosophy, the whole worldly phenomenon as it is experienced in any moment is dukkha, 'pain' or 'suffering', or tanha, 'thirst', 'volition', 'craving'. Overcoming this whole phenomenon is the 'extinction of thirst', or tanhakkhaya, it means one is able to see 'truth', nirvana.
'Mental activity' means 'conditioning', or samkhara, and reproduces dukkha. 'Volitional action' according to Buddhist philosophy is called kamma (not to be with the Western term or the karma in the Vedas). All things that are either kusala, akusala, 'wholesome' and 'unwholesome' are reproducing, they are leading to 'rebirth', samsara, meaning they will lead the mind to more conditioned states.
To come back to your question: Doing something willingly wrong, like lying, can usually be considered more strongly unwholesome. But this is not to say that doing the opposite will save one from suffering. Wanting to do good is just another mental formation.
Loosely speaking, the margin between good and bad is thin, like with most things in the world. Our organisms need salt, but eating several spoons will damage the body severely.
The closer you get to see truth, the more precise you come to describe the world as it is experienced. But for all the different states that we are in, there is a solution to come to a less conditioned state. The Fourth Noble Truth is the Noble Eightfold Path, consisting of a variety of trainings. Mainly those trainings aim at producing 'ethical conduct', 'mental discipline', and 'wisdom', sila, samadhi and panna.
This Buddhist path deals with the Right Speech, samma vaca, it is the 3rd category of the Noble Eightfold Path. (The 4th is Right Action, samma kammanta and might be related to this question also.) Speech should be useful, one can also remain silent rather than engaging in wrong speech.
As I see it, the declaration or phrase used to receive food is more of a gesture. It is a nice act, it can help to implement good habits, it acts as a little reminder. This reminder is karma in the sense of the Vedas or Hindu sense: It is a mere action. The point is that according to Buddhism the mere speech is not kamma, it is just sound. What matters more is mental volition.
The mismatch of the words and the (assumed) behavior of the person receiving the food is neither morally right nor wrong. If the mismatch helps the receiver be actually more careful in his ethical conduct one day, but it also might not do this -- the receiver also doesn't know what will come. But what is considered morally right, is the individual's effort towards a solution.
