"The releasing of the mouth cloth" which is a Jukun burial rite
similar to the Egyptian funerary tradition called "the opening of the
mouth".  I need the information regarding these burial rites in French
if possible

I've not been able to find anything about Jukun burial rites on the
Net.
With respect to the Opening of the Mouth, this was a ceremony used by
the Egyptians to give life to a statue of a deity as well as to
empower a mummy so that the dead person could survive in the
afterlife.

To search for information in French on the opening of the mouth
ceremony, you need to be aware that the name of it is "le rite [or
rituel] de l'ouverture de la bouche"  Try searching on that phrase or
on a combination of words.