If a terminfo file contains non-standardized entries, it will usually drop those when just installed with the default settings. However there is the `-x` option that allows treating those entries as user-defined and adding them as extended table entries (see tic(1M)).

We've recently updated our installation instructions upstream (see https://github.com/jwilm/alacritty/blob/master/INSTALL.md#terminfo), but it seems like this has not propagated down to the Archlinux package yet. Other terminfo packages seem to do the same (see https://git.archlinux.org/svntogit/community.git/tree/trunk/PKGBUILD?h=packages/termite#n65), so it's probably best to follow suit here, since it's likely to cause bugs (see https://github.com/jwilm/alacritty/pull/2134).