\textgreek command unknown with LuaLaTeX since last babel-greek update

greek no longer loads LGR if it detects an unicode engine. But you can do it yourself:

\documentclass{article}
\usepackage[LGR,TU]{fontenc}
\usepackage[greek.ancient,french]{babel}
\begin{document}
\foreignlanguage{greek}{\textgreek{da'imwn}}
\end{document}