> Since I very rarely type in my native tongue on that computer, and I annoyingly frequently have had to reinstall the OS from scratch, I no longer bother with customizing xmodmap or similar things on that computer.

A backup of your home fir, (or at least all dotfiles in it), etcd running on /etc (or $HOME too), and a list of packages that were installed might go a long way towards making setup after reinstall fairly trivial, and you might no longer feel like some customizations aren't worth it.