The relationships themselves are all unique - and are translated individually.
So, "mother's brother" and "father's brother" are two separate relationhips - because they have different names in some languages.
Also, in some languages, a "woman's uncle" is different to a "man's uncle". So, "uncle" can be
a man's mother's brother
a man's father's brother
a man's parent's brother
a woman's mother's brother
a woman's father's brother
a woman's parent's brother
If we try to add half-brothers, there are *many* more combinations. There are probably languages that have different names fro a "half" relationship through a common mother and a "half" relationship through a common father.
So, the number of permutations (and hence separate translations) goes up enormously.
We can probably do more to match partial relationships, (e.g. "father's father's son's wife" could be either "father's half-brother's wife" or "grandfather's daughter-in-law") - but this is not always easy.