I've noticed that the Etruscan letter 𐌙 is sometimes transliterated as "ch", as you can see in the following image of an information panel in the Hypogeum of the Volumnus family:
I can show you a specific example of this practice. In the following image, coming from Wikimedia Commons, you can read the Etruscan word 𐌙𐌀𐌓𐌖, which is the name of the character that is represented next to it:
Now, this character is a psychopomp of Etruscan mythology whose name is usually spelled Charu or Charun, as you can see in this Wikipedia article. By the way, the same Wikipedia article states
[...], words ending in -n after u were disappearing from the language which is why we see his name spelled Xarun and later Xaru.
That is, another transliteration convention based on the use of Greek letter χ, mentioned in this post, is used.
I wonder what is the reason to transliterate 𐌙 as "ch". Does this have to do with the custom to represent as "ch" the unvoiced aspirated back dorsal velar stop sound [ kʰ ] in classical Latin, as explained in this answer? Or is there another reason?