% !TEX program = LuaLaTeX+se
\documentclass[12pt]{article} 
\usepackage{gregoriotex}

\begin{document}

\grecommentary{something}

\gabcsnippet{(c3) Test<alt>test</alt>(g) test<alt>test</alt>(h) test<alt>test</alt>(i) test<alt>test</alt>(j) test<alt>test</alt>(k) test<alt>test</alt>(l) test<alt>test</alt>(m)}

{ % could also be \begingroup
\grechangedim{commentaryraise}{0pt}{fixed}
\grecommentary{something}

\gabcsnippet{(c3) Test<alt>test</alt>(g) test<alt>test</alt>(h) test<alt>test</alt>(i) test<alt>test</alt>(j) test<alt>test</alt>(k) test<alt>test</alt>(l) test<alt>test</alt>(m)}
} % could also be \endgroup

\grecommentary{something}

\gabcsnippet{(c3) Test<alt>test</alt>(g) test<alt>test</alt>(h) test<alt>test</alt>(i) test<alt>test</alt>(j) test<alt>test</alt>(k) test<alt>test</alt>(l) test<alt>test</alt>(m)}


\end{document}