hey--i got it--you need to find some old typewriter keys!!!!
that might work
but that's three different sized fonts too
ver tall order
because
even if you find the corrrect fonts etc
getting the fondant or whatever material to take the impression that crisply will also be a challenge
maybe marzipan or chococlay would be crisper
it could easliy come out rounded
and
piping can def have the straight edges if one is very accomplished at it
i myself tend to stay far away from such accomplishment that small 
oh--'nuther idea--just to help create the illusion--less than perfect but doable and close
so
make your heart charm set, pipe the lettering aside
roll a flat piece of fondant and cut out the same size heart but flat
then center a just smaller heart cutter on that and cut it out, discard the center
now you have an outline to place around the wording so it has the appearance of being recessed
again not perfect but increases the illusion factor--maybe need to make the heart a bit bigger to accomodate
tiffany wishes and heart thoughts for you
