According to Merriam-Webster, a half-truth is 'a statement that mingles truth and falsehood with deliberate intent to deceive', yes, but a bit of searching shows that on-line dictionaries don't have an entry for half-falsehood, and so, in the lack of this definition, the first thing to come to my mind is that one could define it the same way a half-truth is defined 'a statement that mingles truth and falsehood with deliberate intent to deceive'.
Maybe it is so, however a doubt arose as to whether in a half-falsehood there is a 'deliberate' intent to deceive.
I don't know why, but I'm under the impression that one utters a half-falsehood in order to save themselves rather then to deceive other persons, let alone to deliberately deceive them.
Therefore, what's the difference between a half-truth and a half-falsehood?