Werner:
This is the one that I think will help the most (taken from the Fonts
out of Context manual, pp 147 - 148 

"If you want to use Lucida, all you have to do when you have bought the
fonts, is to put
the OpenType files in a place where they can be found, for instance:

tex/texmf-fonts/fonts/data/lucida 

Of course you need to run MTXRUN --GENERATE afterwards so that the files
can be found. 

On 2023-04-25 12:34, lynx--- via ntg-context wrote:

> Hello, Werner:
> Have you tried some diagnostic tests, such as trying to get the PDF output via DVIPS? I suspect that you are, in fact, more knowledgeable and experience with ConTeXt than I am, but for what it is worth you may want to look at: 
> 
> * \setupoutput[dvips,acrobat] (SEE: _Context-The Manual_ (Hans Hagen; English, page 24))
> * \showbodyfont[Options] (SEE: _Not-so-short Intro to ConTeXt (_J. Ataz-Lopez;English, page 114))
> * $ MTXRUN  (mtxrun  is the _ConTeXt TDS Runner Tool_) command from a terminal window it has has a large number of options for finding the fonts installed, and for querying their characteristics (SEE: _Fonts out of ConTeXt _(Hans Hagen, pg 52 and ff))
> 
> Em 
> 
> On 2023-04-25 08:50, Werner Schmidt via ntg-context wrote: 
> Hi conTeXt folks,
> 
> may I ask again. How could I debug the font typesetting of PDF files with conTeXt?
> 
> Any help is highly appreciated.
> 
> Best Werner
> 
> On April 21, 2023 1:29:18 PM UTC, Werner Schmidt via ntg-context <ntg-context@ntg.nl> wrote: Hi all,
> 
> I'd like to use the commercial Adobe Kepler typeface (Kepler Std - version 2.020) in conTeXt (v2023-04-15) as text (serif) font. Although the font files are loaded correctly (see log below), the generated PDF is unreadable (see attached image).
> 
> Notes:
> - Only serif font (keplerstd-light.otf) is not working. It's not embedded in the generated PDF.
> - italics and bold fonts are embedded and are rendered well
> - Can't provide font files because Kepler is a commercial typeface
> 
> Do you have any ideas how to debug this issue?
> 
> Thanks Werner
> 
> log file:
> mkiv lua stats > loaded fonts: 10 files: fontawesome6freesolid900.otf, frutigernextpro-bold.otf, frutigernextpro-regular.otf, iosevka-term-ss09-light.ttf, keplerstd-light.otf, keplerstd-lightcapt.otf, keplerstd-lightit.otf, keplerstd-semibold.otf, latinmodern-math.otf, lmroman10-regular.otf
> mkiv lua stats > font engine: otf 3.133, afm 1.513, tfm 1.000, 30 instances, 18 shared in backend, 3 common vectors, 15 common hashes, load time 0.449 seconds
> Example:
> 
> This text can't be read in PDF.par
> {it However, italics are working.}par
> {bold Also Bold and bfem BoldItalics!}par
> input{zapf} ___________________________________________________________________________________
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> 
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maillist : ntg-context@ntg.nl /
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