hey'll tell you that it's actually /e/ followed by something like a nasal glide. A glide is something like the /j/ sound as in the name Maya.
the 'w' ('ł', short u)) is the glide in this case that is made nasal not the 'y' ('j') - but overall your knowlegde is impressive (definitely way more structured than mine - you must be seriously studying Polish, aren't you?)
Let's say it's a nasal that's in the process of losing its nasality :)
Polish people can perfectly pronounce nasal vowels - the thing is it slows down the speech (it's also called hypercorrect pronounciation because noone speaks that way normally) - and in our normal ways of speech the articulation becomes 'asynchronous' (more or less) where you can more or less distinguish a clear vowel and a nasal glide - as for losing nasality - it's been losing nasality for ages so I don't expect it to lose nasality altogether (not in the age when language patterns are reinforced by the TV)
First of all - same/different and nasal/not nasal are two distinct questions. Obviously it could be pronounced differently whether or not it is nasal.
this is also true - you recognize the issue very well
anyway in Stenka the 'e' vowel is not discerneably nasal coloured - what is more the 'n' when pronounced in Polish is quite unlike the 'n' that English people use in 'nk' groups (as in 'bank') (I don't know how to go about entering the IPA signs - but I'm sure you know what I mean)