Components in this compound:

valsi

x₁ is a word meaning/causing x₂ in language x₃; (adjective: x₁ is lexical/verbal).

tonga

x₁ is a tone/note of frequency/pitch x₂ from source x₃.

morna

x₁ is/reflects/represents a pattern of forms/events x₂ arranged according to structure x₃.