Some of the cirth had different values for the Elvish and Dwarvish languages, and some were used in only one system or the other.
It is said in The Silmarillion that Aulë, the creator of the first Dwarves, taught them "the language he had devised for them," which implies that Khuzdul is technically, in reality and fictionally, a constructed language.
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According to The War of the Jewels, it was learned simultaneously with the aglâb from childhood.
Khuzdul |
It is stated that Finrod Felagund was able to quickly master Taliska purely by determining the various changes undergone by its Avarin component from Primitive Quendian, and Faramir stated that all languages of Men are of Elvish descent, suggesting that Taliska and Adûnaic are in fact Quendian/Avarin with some Khuzdul influence (notwithstanding the possibility that Faramir was misinformed, much as how many people mistakenly think English is a Romance language).
The text is said to mean "Balin son of Fundin, Lord of Moria" in both Khuzdul and Westron, but while the first part of the inscription is in Khuzdul, the second part is actually plain English, just written in certar.