Your second quotes are misplaced:
sed -e 's/\(".*\),\(.*"\)/\1 \2/g'
In addition, using regular expressions tend to match the longest possible part of the text, meaning this will not work if you have more than one quoted field in the string.
A way that handles multiple quoted fields in sed
sed -e 's/\(\"[^",]\+\),\([^",]*\)/\1 \2/g' -e 's/\"//g'
This is also a way to solve this, however, with input that may contain more than one comma per quoted field the first expression in the sed would have to be repeated as many times as the maximum comma content in a single field, or until it does not change the output at all.
Running sed with the more than one expression should be more efficient than several sed processes running and a "tr" all running with open pipes.
However, this may have undesired consequences if the input is not properly formatted.
i.e. nested quotes, unterminated quotes.
Using the running example:
echo '123,"ABC, DEV 23",345,534,"some more, comma-separated, words",202,NAME' \
| sed -e 's/\(\"[^",]\+\),\([^",]*\)/\1 \2/g' \
-e 's/\(\"[^",]\+\),\([^",]*\)/\1 \2/g' -e 's/\"//g'
123,ABC DEV 23,345,534,some more comma-separated words,202,NAME