I eventually got this to work, though honestly I don't remember what finally did the trick.
Partly, I think I had wrong assumptions about how that save/edit/delete drop down works. I assumed I could configure a visual style with the sliders and settings in that editor, then type a name for that style into the save box, click "save" and have a new style in my .ini.
That does not appear to be how it works. That is only a dropdown, not a text entry box. So I had to define all my styles in the .ini first. I made a "default," a blue one, and a green one. It doesn't matter so much that you get the style right. In fact, at first you could just copy/paste the default style and rename it. Because once it exists in the .ini file, then you'll be able to load it into that editor, tweak and adjust it how you want and save it.
I'm away from my cab, but I'll try to remember to come back and post my .ini file later.
is the point of these to be displayed over the existing score displays on the b2s??
That is what a lot of people do. Maybe most. I want to use the alphanumeric displays in my DMD (emulated with Freezy on an LCD screen). The dot matrix display just doesn't look right to me on a lot of games that used the alphanumeric displays.