I'm sorry for the delay in responding to this.
Here's a way to make a 5 star rating system with pseudo 1/2 stars (shown as unfilled stars).
You're going to make a new user field of type Decimal. You'll use this field to set the rating. This is where you'll rate your tracks, and will ignore the stock [Rating] field.
Anywhere you want to see the Stars, you'll enter the expression:
mid(★★★★★, 0, [rating (mine)])/
ifelse(math(equal([rating (mine)] % 1, .5)),☆)
This can be in an expression column, a category, thumbnail or caption text.
The results will look like the attached image.
To create the new User field of type decimal:
Tools > Options > Library & Folders > Manage Library Fields... > Add New Field
and enter Rating (mine) as the new field name. Set the User data: Data Type to Decimal, and click OK.
Now, to test it out, in a files list in some view, add two new columns by right-clicking somewhere in the header, and and enable the Rating (mine) field. Then do it again, this time selecting Add Expression Column... and enter the expression above, and give it a name such as Rating Stars (mine).
Now you can set your values in the Rating (mine) field and see the stars reflected in the Rating Stars (mine) column.