Try
\switchtotypeface[LeagueScript][12pt] \switchtobodyfont[LeageScript]
Is \switchtobodyfont the recommended way of changing the typeface temporarily anywhere in a document (for example when making cover page graphics)? Its name implies only document body. Nevertheless, \switchtobodyfont works (at least in the document body, haven't tested yet elsewhere) without setting \setupbodyfont.
\definetypeface[LeagueScript][ss][specsans][League Script Thin] \definetypeface[Pompadour][ss][specsans][Pompadour]
This seems to work for most fonts, with others like Pompadour it fails (pompadour has SubFamily string of "Black" [Mac] and "Regular" [Windows] in the .otf), and spec fails to find pompadour-normal-normal which it is looking for). Pompadour is a serif font, so i tried also with arguments [rm][specserif]. I have looked into co-typography.pdf for help, and while it is very extensive in some parts, in others it is (too) technical and lacks expanations for some parameters. As soon as I get these issues sorted out I'll try if I can make the MKIV font pages in the Wiki a bit more beginner friendly. Best regads, Otso Helenius