Hi cageybee,
If you look at the node description of the String Manipulation node, you can see that special characters such as backslashes need to be escaped using a backslash. For instance, a single backslash in a string is written as two consecutive backslash characters; the first one acts as the escape character for the second.
The same holds if you're replacing your string with a Java Snippet node.
So just use ,\\B(\\s\\W){1,} instead of ,\B(\s\W){1,} and it will work.
I also tried to remove the trailing commas with (\,\s)+(\W|\s), you can find attached a sample workflow with both solutions and a Java Snippet node solution.
Best,
Anna