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Perl, 81 79(?) bytes
Gee, you guys are all using variables! Who needs variables? :)
Here’s the simple code, which is just 79 bytes, most of it taken up by silly identifiers(but not variables :):
use Math::Random;s/\pL\K/(x x random_normal 1,10,5)=~s,.,chr 768+rand 48,reg/eg
But I’m not quit...