After-preamble with polyglossia

[Folsk Pratima]

\addto\captions<my_lanuage>{%
  \renewcommand{\figurename}{I LOVE LYX}%
}

does not work after \begin{document} and there is no way to put it
after \usepackage{polyglossia}. I am enraged!

LyX 2.3.7 (2023-01-01)

Should I compile whatever is the latest version to fix this? It feels
so dumb to handcraft a file with LyX to end up compiling it with
xelatex on command line, because LyX does not allow me to mess with
polyglossia!

Sorry if missed some info I am very angry and I want to sleep and I
still have not finished with my documents.