MacOS – Font is installed in font book, but bold does not work

I'll bet you have a font corruption problem.

1. Split the uninstalled fonts into two groups.
2. Import the first group.
3. Check to see if they imported successfully.
   • If yes, you know the problem is in the second group, so go to step #1.
   • If no, the second group might be okay, so try importing that.

And so on.

You should be able to narrow down the problem without having to import each font one at a time. But my guess is that one or more of your fonts is corrupted.

When I view this page in Firefox (12.5 beta) I am seeing this text as you probably intended it - no bold and/or italic. Since you reported that the problem is occurring in both Safari and Firefox, it likely is not user preferences in both browsers, which can be set to use user-defined fonts instead of those dictated by CSS or HTML instructions. Nevertheless, I'd check each browser's display preferences first to see if this isn't the case.

Otherwise, this may be a problem with your fonts cache, so clearing it may solve your problem. You can easily do this by opening up Terminal.app and entering the following command (this clears the font cache for the current user account; if you have other accounts, they won't be affected):

atsutil databases -removeUser