Yet again AutoHotKey saves the day with ALT+N.
my code for AHK and working:
Dear EverNote Team - please make sure in the next update that all polish diacritics are OK, i.e.:
a + LALT = ą
e + LALT = ę
o + LALT = ó
s + LALT = ś
l + LALT = ł
z + LALT =ż
x + LALT = ź
c + LALT = ć
n + LALT = ń