This entire section is purely speculative as there is no official information on the subject that would confirm this. The following table is only an approximation based on an educated guess.
Note that  only appears in Brânk while Û and KH only appear in Khamûl, the latter of which may not be included in Rhûnnic.
Y only appears in the word DYÚL, so It might not represent a separate phoneme, but rather change the D sound into one that’s similar to the Czech and Slovak Ď or the Hungarian GY.
It is also possible that the N in the words NÍ and *NIM is pronounced as /ɲ/, the same way the N in the word new is in some dialects of English.