So, /y/ sounds /i ~ ɨ~ ɪ ~ ə/ and /u/ does the same?
u has no 'schwa' sound. There are links to explanations and examples of pronunciation in these posts - https://www.duolingo.com/comment/13199969
gweiadur.com has real-voice recordings of many individual words.
Both of you could be wrong
I leard so much like this comment of u agree
Bore da dydd marwth ydy