As long as I’m comparing Chinese with Eastern European languages, the phonemic palatal/retroflex opposition is found in Polish, which I found out when working with a Polish woman who had studied a bit of linguistics and comparing notes.
Palatal:
q = ć (should display as c with an acute accent)
x = ś (s with an accent)
j ~ ź (z with an accent)
Actually, the Polish affricate to match Chinese j is dź, but ź fits in the phonemic grid better for comparison with the Chinese palatal series.
Retroflex:
ch = cz
sh = sz
zh ~ rz or ż (should display as z with a dot on top) - phonemically, although drz is the corresponding affricate.
The consonant cluster trz is pronounced the same as cz (like English “ch”) . So in case anyone was wondering how to pronounce Yastrzemski in the original Polish, it’s approximately yas-CHEM-ski. Brezinski = bzhe-ZHIN-ski.
Dental:
ts = c
s = s
z ~ z (phonemically, although Polish dental dz is the corresponding affricate)
Not only that, the Polish nonpalatal vowel y is in complementary distribution with the palatal i, as far as I can tell from a quick glance through a Polish word list. I always find y following retroflex consonants (including the letter r), and i following palatal consonants. This corresponds closely with the two different Chinese vowel sounds of i after retroflex or dental consonants (sounds like Polish y, a back vowel) and after palatal consonants (sounds like Polish i, a front vowel). In both Mandarin and Polish, r is the fourth member of each retroflex series.
Sanskrit has the corresponding 3-way series, but only for unvoiced fricatives:
palatal श ś
retroflex ष ṣ (should display as s with a dot under it)
dental स s
Likewise in Sanskrit, /r/ is associated with the production of retroflex phonemes.
The correspondence of Polish voiced consonants with Chinese unvoiced ones, and Polish unvoiced consonants with Chinese aspirated ones, isn’t phonetically exact, but it does make the series line up nicely with one another.