… because when i want type word: “śmiesznie”, with ś i need to use AltGr + s and then file is saved, cant type it in edtor 
so the hotkey combo for save is getting in the way of adding the special char? How do other apps work for saving? Do they have a different default key combo?
I don’t have any problems in WordPress for example, i don’t know how it is working, but in Polish language, letters as: ś, ź, ć, ę, ą are made with use of “right” Alt button, always and in all software type.
Please create an issue here: https://github.com/getgrav/grav-plugin-admin/issues