I need to make a typeface to extend Proxima Nova — namely a double macron and double breve. I’ve been trying to do this by building glyphs in the Private Use Area, but when I test the letters in Publisher the text baseline gets moved down. The metrics are exactly the same as Proxima Nova so I don’t know what I’m doing wrong.
My standard desktop license does allow user modification, so long as the modified font is not shared or distributed among anyone other than users covered by the purchased license. Note: A few of my distributors sell a different desktop license, and it it not usually allowed by webfont licenses.
Regarding the vertical metrics, it seems possible that importing from a font file might not be giving you the correct values, or possibly some are missing. Here are the values in the original source files: