I did a test with Windows 10.

Installed a fresh copy from the garden, Got the GFS Didot font from Google
Fonts, and installed it system-wide (C:\Windows\fonts). After that, I ran

mtxrun --script fonts --reload

Then tried the pattern suggested but did not work. However, then I tried a
pattern without asterisks:

mtxrun --script fonts --list --pattern=didot --all

This returned the font:

C:\griego>mtxrun --script fonts --list --pattern=didot --all
identifier           familyname    fontname             filename
                        subfont   instances

gfsdidot             gfsdidot      gfsdidotregular
 c:/windows/fonts/GFSDidot-Regular.ttf
gfsdidotnormal       gfsdidot      gfsdidotregular
 c:/windows/fonts/GFSDidot-Regular.ttf
gfsdidotregular      gfsdidot      gfsdidotregular
 c:/windows/fonts/GFSDidot-Regular.ttf
theanodidot          theanodidot   theanodidotregular
c:/windows/fonts/TheanoDidot-Regular.ttf
theanodidotnormal    theanodidot   theanodidotregular
c:/windows/fonts/TheanoDidot-Regular.ttf
theanodidotregular   theanodidot   theanodidotregular
c:/windows/fonts/TheanoDidot-Regular.ttf

trying to render Pablo's example didn't work at first, but after i called
the fonts with the name returned by mtxrun:

\mainlanguage[agr]
\definefontfamily[mainface][rm][gfsdidot]
\definefontfamily[mainface][ss][theanodidot]
\setupbodyfont[mainface]
\starttext
GFS Didot:

\doloopoverlist{\tf, \it, \bf, \bi}
  {\recursestring\input aristotle-grc\par}

\ss
Theano Didot:

\input aristotle-grc
\stoptext

Everything compiles correctly, and the font is used. Since it's only a
single font file with no variants, you don´t get italics, bold etc. But the
font is being used.

-- 
Andrés Conrado Montoya
Andi Kú
andresconrado@gmail.com
http://sesentaycuatro.com
http://messier87.com
http://chiquitico.org
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Los fines no justifican los medios, porque la medida verdadera de nuestro
carácter está dada por los medios que estamos dispuestos a utilizar, no por
los fines que proclamamos.
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