consonant mutations

[Stefan]

Perhaps worth mentioning is /n/ > /ð/ before /r/ in Sindarin, as in Caradhras. If it was good enough for JRRT...

Considering Tolkien's background I expect this was inspired by Old Norse, e.g. Proto-Germanic *mannz "person" > *mannR > Old Norse maðr > Icelandic maður [maːðʏɾ̥]
(where R is used to represent a segment in early Old Norse whose realisation is not entirely clear)

[Jonlang]

Perhaps worth mentioning is /n/ > /ð/ before /r/ in Sindarin, as in Caradhras. If it was good enough for JRRT...

Considering Tolkien's background I expect this was inspired by Old Norse, e.g. Proto-Germanic *mannz "person" > *mannR > Old Norse maðr > Icelandic maður [maːðʏɾ̥]
(where R is used to represent a segment in early Old Norse whose realisation is not entirely clear)

I've also heard that the name Caradhras came to him first, meaning he had to make caran and ras fit, which seems entirely plausible after reading articles in Vinyar Tengwar. This is, apparently, because Tolkien liked the sound of the Welsh mountain Cadair Idris /ˈkad.(ɛ)r ˈɪd.rɪs/, but this may or may not be true.

[Vardelm]

I've also heard that the name Caradhras came to him first, meaning he had to make caran and ras fit, which seems entirely plausible after reading articles in Vinyar Tengwar. This is, apparently, because Tolkien liked the sound of the Welsh mountain Cadair Idris /ˈkad.(ɛ)r ˈɪd.rɪs/, but this may or may not be true.

This sounds very in-character for JRR.