Can't write proper Actions scrip to achieve need

This looks utterly redundant.
Why shouldn't it work to replace all hyphens directly to blank minus blank? If it works for the leading and trailing tilde, then it shold work for any other printable character.
I would bulk replace all hyphens with blank hyphen blank and add another "Replace" action in the same action to replace double-blanks with a single one.

Coming to the slash problem:

Yes, go ahead. Although I doubt that it will change a lot.
I encountered the problem that you describe with something more mondane like AC/DC or De/Vision where I suddenly found a group called AC and one called DC in the list shown by the Windows Media Player.
My workaround was to use a character that looks like a slash but isn't: AC⁄DC
Perhaps that is an alternative for you, too.

This is correct as WMP uses the slash as a separator. Not the best choice in my opinion, but MS has been using this for a long time and likely didn’t envision this usage case.

@78rpmuser Unfortunately in some cases characters may not be as they seem. The additional space characters could possibly be alternate characters? Or you have extra spaces in your actions? These cannot be added by Mp3tag without guidance otherwise.

Thanks again for all yours and a couple of others efforts on my behalf. I tried using the version of slash that appears in the numeric portion of the keyboard, but that had the same result as the slash in the alpha portion. I also can't see how leaving the ORIGINAL FIELD blank will be able to convert the double blanks to a single blank on each side of the hyphen. Anyway, your suggestion of replacing the hyphen with any other character than slash made me think to try the back slash and the result is quite satisfactory. e.g. Al Dubin\Harry Warren; is how it now appears in the mp3 file's Property and thus still a single entity, but clearly 2 separate names. My plan now is to run the action against my 5000 records folder, 500 at a time and then for each 500 perform a find \ and if in e.g. Olivia Newton\John, manually replace the \ with a hyphen.
Thanks once again for all your help. This post can now be closed.

I don't know where this comes from.
Naturally,if you want to replace 2 space characters with a single one, you would have to enter the 2 space characters (in my words: blanks) as search term and a single one as replace term.

The backslash may lead to better results in the display of tags - but if you intend to use the data with a backslash character from the composer field then please note the the OS interprets the backslash as separator for foldernames in the filename. so you may end up with a folder Olivia Newton that has a subfolder John.

Yes, this is in fact the same character.

The forward slash that @ohrenkino mentioned above (I.e. AC⁄DC ) is a Unicode character, not from the standard keyboard. Try copying it from this post, it is the same way I use this character in my library to avoid unexpected separator actions.The same can be done for other similar characters. Like the space character, there are many variations in Unicode like half space, I count at least 12. This is a great way to circumvent several system characters that are found on the standard keyboard.