I agree that text faces should aim for invisibility, that "crystal goblet" thing. Are there general rules that can apply to the design of any script face?
As a starting point, I took DEC Terminal, a very clean font that comes standard on Unix systems. The reimplementation is scaled up from 10pt to 12pt.
One of the first things I notice is that single-pixel lines start to look a bit thin at 12pt. Many scripts are too busy to have sufficient detail at smaller sizes. Maybe a mix of thick and thin lines will sometimes be required for sufficient darkness.
How clean does it look? I don't like the regular g; the lower bowl is too flat. I notice that most older fonts use the double-decker g. Maybe it seemed less marked because it was more common in print. That points to a major issue. In translating a printed script to a screen font, how important is it to adhere to the print conventions?
The bold version looks better to me, though I'm having second thoughts about the g and y. I raised the bowls off the baseline because I thought they looked more balanced. After looking at text samples for a while, though, I now think they stand out too much that way. With the aim of invisibility, can we say that consistent repetition of elements is more important than visual balance of individual characters?
One more observation. Older fonts tended to follow the traditional outlines of printed letters, but more recent ones avoid lines that are slightly off horizontal or vertical. This gives a boxy effect but results in smoother outlines. I wonder how long it takes a user community to accept such an adaptation.