Title basically says it all. I wasn't able to locate any information concerning what specifically Font Book thought was wrong with these fonts. I went ahead and installed them, installed Pressure-for-Steam, and selected it as my Steam skin. Everything runs smoothly (excellent theme, by the way).
edit: though the above picture shows only 1 font, this same message is presented for all of the packaged fonts.
I'm running macOS 10.11.6.
Title basically says it all. I wasn't able to locate any information concerning what specifically Font Book thought was wrong with these fonts. I went ahead and installed them, installed Pressure-for-Steam, and selected it as my Steam skin. Everything runs smoothly (excellent theme, by the way).
edit: though the above picture shows only 1 font, this same message is presented for all of the packaged fonts.