but I'm already stumbling about the next thing. while playing around with
some nice fonts I also tried out `optima' (like palatino by h. zapf).
so that is what I see:

mtxrun --script font --list --all --name --pattern=*optima*

optima             optimaextrablack   /System/Library/Fonts/Optima.ttc   index:  0
optimablack        optimaextrablack   /System/Library/Fonts/Optima.ttc   index:  0
optimabold         optimabold         /System/Library/Fonts/Optima.ttc   index:  3
optimabolditalic   optimabolditalic   /System/Library/Fonts/Optima.ttc   index:  1
optimaextrablack   optimaextrablack   /System/Library/Fonts/Optima.ttc   index:  0
optimaitalic       optimaitalic       /System/Library/Fonts/Optima.ttc   index:  2
optimanormal       optimaitalic       /System/Library/Fonts/Optima.ttc   index:  2
optimaregular      optimaregular      /System/Library/Fonts/Optima.ttc   index:  4

then, when using, e.g.,

\definefontfamily [mainface] [serif] [Optima]
\definefontfamily [mainface] [sans]  [Optima]
\definefontfamily [mainface] [mono]  [dejavusansmono] [scale=0.865] %dejavumono/optima x-height ratio
\definefontfamily [mainface] [math]  [TeX Gyre Pagella Math]
\setupbodyfont[mainface,11pt]

neither \it nor \bf (italic and bold) variants are working in the body text (but are just rendered
in the regular \rm font).

I guess your context version is too old because the current version in the standalone
installation of context shows the italic and bold styles.

Wolfgang