Dictionary - Changing language of spell checker

[Stefan-B-Martens]

By default, on my en-US Win11 machine Session uses an en-US spell checker. But I don't even have the corresponding file en-US-10-1.bdic on my machine.

When I install session on a de-de Win11 machine, I find an additional folder "Dictionaries":
.\AppData\Roaming\Session\Dictionaries\en-US-10-1.bdic
And I find
.\AppData\Roaming\Session\en-US-10-1.bdic

Both do not exist on an en-US Win11 machine!

In German Win11 I can replace en-US-10-1.bdic with de-DE-3-0.bdic, rename it to en-US-10-1.bdic.
Now I have a German spell checker.

But how can I change the en-US-spellchecker on my en-US Win11 machine to an German spellchecker?
Any help would be appreciated very much.

[Stefan-B-Martens]

Additional Information
Installed the portable Version of Session on a de-de Win11 machine.
In the portable program folder, I find:
D:\PortableApps\SessionPortable\Data\Profile\Dictionaries\en-US-10-1.bdic
As before,

• I delete en-US-10-1.bdic
• copy de-DE-3-0.bdic to folder Dictionaries
• and rename this German dictionary to en-US-10-1.bdic.

This "trick" works fine: I now have a German spell checker, when typing messages.

However, when I use this portable program folder of Session in an en-US Win11 OS, Session does not use my "fake dictionary",
as now the spell checker is set to en-US again.

Obviously, Session detects when I'm in an en-US-Windows OS and uses some kind of dictionary from my en-US-Windows OS.
Session only uses the dictionary file in D:\PortableApps\SessionPortable\Data\Profile\Dictionaries\en-US-10-1.bdic, when it cannot find any English dictionary in the Windows installation.

There must be a solution to this and I hope that somebody will help me with this problem.