Dear Giraffe07,
I have been experiencing exactly the same problem as you, but with some Fonts of the Futura Family. And, like you, I have not stumbled upon a solution.
I bought Futura a while ago. It has been working perfectly with Lion, but, under Mountain Lion, not all types continued to do so: Futura Bold and Futura Light can no longer be used in iWork applications. Here, in all iWork applications, the characters are "squashed", ie., the kerning is off. This does not happen in Font Book or any other application. Manually adjusting kerning in iWork, however, does not work, as this will just put them farther apart but not correct the problem, as the wrong offset is now just kind of spread out. So it is a problem of how iWork sets these characters in these families. Here is how the affected fonts look like in Keynote. Interestingly, the corresponding Italic fonts are not affected. Go figure.
Like you, I have tried EVERYTHING mentioned here, setting up new accounts, cleaning cashes, removing fonts, reinstalling fonts, you name it. Nothing worked.
This has been extremely frustrating as I have worked months on developing and perfecting a Keynote layout using these fonts, and simply replacing the fonts will not work for me. There is a reason I used Futura, and Futura Bold cannot be replaced by, for example, Futura Heavy. As I have only switched my MacBook Air to Mountain Lion, but not the MacBook Pro, I am not completely screwed up.
To conclude, it seems that this is a bug in iWork under Mountain Lion. I will go the Apple Store this week and ask one of their Masters of the Universe to see what is written in the Kabbalah about this. I cannot understand how this kind of major screw up can happen to a company that has been synonymous with desktop publishing, and here to their very own flagship applications in that sector -- how can it be they don't work any more within their own ecosystem? I just don't get it.
The alternative for me would be to use for InDesign for presentations. But I am not yet prepared to invest in this.