Substrates in Reconstructed-PIE itself??

Regardless of the Urheimat's location, it is impossible that outside
words did not enter the Proto-Indo-European language - on that, we
are surely agreed.

Now, if the Urheimat is indeed in Ukraine [it's rude to call it THE
Ukraine] and Southern Russia, archaeological evidence tends to
suggest that there were several societies that came together as one
to form what could well be the Proto-Indo-Europeans. The Sredny-Stog
and Khvalynsk culktures [the latter of which likely arose out of the
Samara culture] seem to have likely come together to form the
nomadic, conquering Yamna/Pit-Grave culture. Now, it seems quite
probable that these cultures, despite archaeological closeness, did
not speak the same language. The Sredny-Stogs did much trading with
the Tripolye culture to the West, and likely adopted a few terms
from them. Now, since the Sredny-Stogs already had elements of
another language influencing them, their language would DEFINITELY
be different from the Khvalynsk tongue. Then, when the Khvalynsks
and Sredny-Stogs somehow got together, there would almost certainly
have been a further mixture of terms.

My point? Perhaps we can begin to see if there are any seeming
divergences in the forms of the words we have reconstructed. Of
course, exactness is impossible, HOWEVER, that does not stop an
attempt. Expecially considering the number of likely roots that
exist, this should be all the easier. This task might well be aided
by synonyms for the same idea, after teasing out possible semantic
shifts.