hin or chin?

[William Cloud Hicklin]

If it was supposed to pronounce as K, why didn't Christopher change it to Khîn instead of Hîn? C was always pronounced as K in Elvish, but ch was a phone of its own.

JRRT decided (while the LR was in galleys) not to use K in transliterating Elvish.* Latinate as he was, he assumed, optimistically, that readers would automatically understand that C is always 'hard.' He reserved K as a visual marker of non-Eldarin tongues: Khuzdul, Adunaic, Black Speech.

CT disagreed at the time (note that on The Map it was still "Kirith Ungol"), being perhaps more realistic, and years later in his own pronunciation guide emphasized "not Seleborn." But he wasn't going to violate the Rule.

*This rule didn't apply to certain names associated with the Valar: Tulkas, Melkor. This internally Tolkien explained (very late) as being because these names weren't Eldarin, but Elvish approximations of Valarin (tho' there's no justification in tengwar for the distinction!)- but externally, of course, because these early names belong to the foundational, Finnish-based layer, K being common in Finnish.