You can use dpkg with the -S flag to identify the package that installs icons in the path /usr/share/m17n/icons
It is used to install/manage individual packages, in this case to identify which is the package to reinstall.
From man dpkg:
NAME
dpkg - package manager for Debian
SYNOPSIS
dpkg [option...] action
[...]
DESCRIPTION
dpkg is a tool to install, build, remove and manage Debian
packages. The primary and more user-friendly front-end for dpkg
is aptitude(1). dpkg itself is controlled entirely via command
line parameters, which consist of exactly one action and zero or
more options. The action-parameter tells dpkg what to do and
options control the behavior of the action in some way.
dpkg can also be used as a front-end to dpkg-deb(1) and
dpkg-query(1). The list of supported actions can be found later
on in the ACTIONS section. If any such action is encountered dpkg
just runs dpkg-deb or dpkg-query with the parameters given to it,
but no specific options are currently passed to them, to use any
such option the back-ends need to be called directly.
[...]
-S, --search filename-search-pattern...
Search for a filename from installed packages.
Open a terminal and run dpkg -S /usr/share/m17n/icons/ to see that the impacted package is m17n-db
$ dpkg -S /usr/share/m17n/icons/
m17n-db: /usr/share/m17n/icons
Therefore, it's enough that you run the command: sudo apt --reinstall install m17n-db
