First, berate whoever did that, because what they typed would become
the actual text of the final version if it doesn't get corrected.
Turn off Track Changes for a moment. Hopefully there aren't any proper
names in their additions, because you can click the "Go to next
change" arrow, then choose Change case > Sentence case for each change
(or, if they don't include complete sentences, Change case > Lower
case). I don't think you can put a Chnage Case command into Replace
With, so either you have to do each one individually, or someone will
write a macro to do it for you. (But would the macro be able to choose
between Sentence case and Lower case when necessary?)
If, on the other hand, they didn't actually type in all caps but
simply used a font that has no lowercase, such as Copperplate Gothic,
then just Find > Find What? > More > Format > Font > (the name of the
offending font); Replace With > Format > Font > (the correct font);
Replace All.
