Most foundries won't find it worth it to try to nail you for USING a knockoff or pirated copy of their font; if you try to sell the font itself, on the other hand, that'll provoke them.
It's almost impossible to trademark or copyright the appearance of a font; any enforceable IP rights are generally held to apply to physical/electronic media that provides an accurate representation of the font. Most foundries realize this; that's why you can get clones of popular fonts, and nothing stops them from being released in the first place - Arial was an intentional (professional) clone of Helvetica, and nobody went after Monotype (I think) or Microsoft (who contracted for it) for doing it.
One way that foundries make money on their most common fonts is to MAKE them common, by licensing them to software publishers such as Microsoft or Corel to include in graphics or office suites, or even as "Core OS fonts". Thus, damn near everyone has Arial and Times New Roman today, and most of those who don't have Helvetica and Times Roman instead.
Offhand, I'd say "don't worry about it" - if you've got an Optima or ZapfHumanist font, or a clone of them, go ahead and use it for your Traveller stuff - provided you're NOT doing it in a way that would have you tripping over Trade Dress issues.
(Freelance Traveller uses ZapfHumanist for our masthead and heavily for titles throughout the magazine; we avoid the Trade Dress problems by using full-page cover images instead of the solid black that has come to signal 'Traveller'.)