Add this fix to your document:

\unprotect

\def\typo_delimited_fontdriven
   {\dontleavehmode
    \begingroup
    \dostarttaggedchained\t!delimited\currentdelimitedtext\??delimitedtext
    \usedlanguageparameter{\c!left\currentparentdelimitedtext}% was: 
\currentdelimitedtext
    \usedelimitedtextstyleandcolor\c!style\c!color
    \typo_delimited_start_content
    \bgroup
    \aftergroup\typo_delimited_fontdriven_e
    \let\next=}

\protect

There was a bug when “method=font” was used but this was fixed last October.

Wolfgang
> Tomas Hala <mailto:tomas.hala@mendelu.cz>
> 21. April 2018 um 18:01
> #
> # unfortunately, this does not work (on my computer with TL2017).
> #
> # Proper Czech quotation marks are available via \quotation command:
> # \mainlanguage[cz]
> # \quotation{text}
> #
> # But it is language independent problem, I did more tests:
> # neither Czech, nor US, nor Dutch, nor German quotation marks are
> # hanging.
> # Without influence is also font (font family), tested on modern,
> # libertine,
> # EB Garamond 12 from your example, times...
> #
> # No change appeared switching the order of commands
> # \definefontfeature and \setupalign.
> #
> # \setupdelimitedtext[quotation][method=font]
>
> I tried it but it generates an error -- "Extra }, or forgotten \endgroup",
> after run till the end, the opening character is hanging but closing
> character disappeared. (Similarly with \setupquotation[method=font].)
>
> Tomáš
>
>
> # Wolfgang
>
> \starttext\showframe\mainlanguage[cz]
> \definefontfeature [default] [default] [protrusion=quality, 
> expansion=quality]
> \setupalign[hz,hanging]
>
> \setupdelimitedtext[quotation][method=font]
>
> \setupbodyfont[times] % libertine, times, modern
> \quotation{pokus s uvozovkami}
> \stoptext
>
>
>
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