File name transliteration
I applied a Drupal 8 core patch from this page. It seems to work fine. It adds a new option to /admin/config/media/file-system:


This option enables transliteration for all future uploads to all file fields. It also works for inline images when Enable image uploads is enabled (for the text-format). I don't know if the patch affects IMCE, since IMCE was not installed on my test installation.