Help with a regular expression

Here is how the track titles currently read:

Sinfonia No. 2, cm, BWV 788
Sinfonia No. 3, d, BWV 789

I want to change them to:

Sinfonia No. 2 in cm, BWV 788
Sinfonia No. 3 in d, BWV 789

Here is my regular expression that I thought should work. I replace:
(/d+), ([abcdefg#m]+)
$1 in $2

Unfortunately, it doesn't work - nothing happens. I have verified that the action type is "regular expression" and it's searching in the correct tag field ("Title").

Maybe this:

Regex: '(.+\d+),(.+),(.+)'
Replace with: $1 in$2','$3

That would produce too many false positives - I'm going to use these scripts for all classical CDs to come in my collection. But you still helped me... you know what was wrong??? I put /d instead of \d.

= faceplant =