Resolve Umlauts language specific so that ä becomes ae and not a

Problem/Motivation

So I am using pathauto to create reasonable URLs for my nodes.

When the language of said nodes is set to German, umlauts ä ö ü will get changed to ae, oe an due which is best practice.

I figured that if I change the language of a node to english, ä will get transormed to a.

So far so good.

Now in addition to nodes I also rename image and file paths of said nodes using File (Field) Path.

So for file names ä ö ü will always be resolved to a o u (instead of ä ö ü) no matter what.

I suspect this to happen because file names and attachment fields don't have a language parameter themselves (unlike nodes).

Do you think there is any way to still manage to have umlauts being resolved correctly?

(The interesting part is that in the Drupal 7 version this worked. I suspect it to be like this because in Drupal we could set patterns also for fields / file locations rather than just in the field setting themselves.)

Steps to reproduce

have file names and paths with umlauts being resolved.

Proposed resolution

have language specific transliteration like it is handled by pathauto for nodes.