The \exg command is much more complicate than \eg, because it parses the text to horizontally align the words of two lines.
Some TeX engines (pdfTeX, LuaTeX, XeTeX) support the "savepos" feature. It allows to record the current position (unit is sp) in the .aux file to be evaluated in the next TeX run.
The following example uses this feature together with zref, a packages that provides more flexible label/ref system than the standard \label/\ref provides.
\RequirePackage{ifluatex}
\ifluatex
\IfFileExists{luatex85.sty}{\RequirePackage{luatex85}}{}
\fi
\documentclass[twoside]{article}
\usepackage[
a6paper,
landscape,
vmargin=1cm,
includeheadfoot,
showframe, % for reviewing
]{geometry}
\usepackage{linguex}
\usepackage{zref-savepos}
\makeatletter
\zref@newprop*{PageValue}[1]{\the\c@page}%
% Counter
\newcount\eolpos@cnt
\eolpos@cnt=\z@
\newcommand*{\eolpos@label}{eolpos\the\eolpos@cnt}
\newcommand*{\eolpos}{}
\protected\def\eolpos#1{%
\leavevmode
\rlap{%
% Unique label names
\global\advance\eolpos@cnt\@ne
% Save the current horizontal position along
% with the value of the page counter
\zref@savepos
\zref@labelbyprops{\eolpos@label}{posx, PageValue}%
% Measure part
\sbox\z@{#1}%
\dimen@=\z@
\zifrefundefined{\eolpos@label}{%
}{%
\dimen@=\dimexpr
\expandafter\ifx\csname pdfhorigin\endcsname\relax
1in%
\else
\pdfhorigin
\fi
+%
\ifodd\zref@extractdefault{\eolpos@label}{PageValue}\@ne
\oddsidemargin
\else
\evensidemargin
\fi
+\textwidth
-\wd\z@
-\zref@extractdefault{\eolpos@label}{posx}{0}sp%
\relax
}%
% Set space
\ifdim\dimen@<\z@
\typeout{`eolpos` warning: Text sticks to the left by \the\dimen@}%
\fi
\kern\dimen@
% Place user text
\usebox\z@
}%
}
% \z@ = 0 or 0pt
% \@ne = 1
% \dimen@ = \dimen0
\makeatother
\begin{document}
\ex. Some Example French sentence \hfill(French)\\
This is the gloss\\
`the interpretation'
\exg. Some Example French sentence \eolpos{(French)}\\
This is the gloss\\
`the interpretation'
\newpage
\ex. Some Example French sentence \hfill(French)\\
This is the gloss\\
`the interpretation'
\exg. Some Example French sentence \eolpos{(French)}\\
This is the gloss\\
`the interpretation'
\end{document}
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\documentclassand ending with\end{document}that shows your problem, to save us the work of making up a compilable document? – gernot Jan 28 '17 at 09:53