What you are looking for is text streams. They are not yet fully
functional in mkiv. But as long as you need the streams to appear
as columns on the same page, as seems to be the case, there is a
cheap workaround using the *tabulate* environment (see below).

The great thing about \{start,stop}tabulate is that it allows for
page breaks inside paragraphs of arbitrary length.

Regards
Philipp


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\newcount\progresscounter \progresscounter0
\def\placeprogresscounter{%
  %% caution when using dynamic content: check
  %% for first pass to avoid multiple executions
  \iftrialtypesetting42\else
    \advance\progresscounter\plusone
    \the\progresscounter
  \fi
}

\starttext

\starttabulate[|r|p|p|]
  \NC \placeprogresscounter
  \NC \language[deo] Hallo, Welt!
  \NC \language[en]  \input knuth
  \NC\NR
  \HL % ????????????????????????%
  \NC \placeprogresscounter
  \NC \language[deo] N?chster Abschnitt!
  \NC \language[en]  \input ward
  \NC\NR
\stoptabulate

\stoptext

\NC \language[deo] Hallo, Welt!

\NC \language[en] \input knuth

\NC\NR

\NC \language[deo] Nächster Abschnitt!

\NC \language[en] \input ward

\NC\NR

\stoptabulate

Huseyin