I would suggest adding this setting because if you write your journal entries in other language than your system language is then you can't use the spell check.
In my case my system language is english and i write my journal entries in german.
Or a other solution suggestion is that you get the spell check language from the keyboard language like one note it does.
I hope its clear what i mean.
Best Greetings FlionkJ
Add setting for selecting spell language checking