Hardware Keyboard for iPad/iPhone Produces Wrong Characters

This problem is normally caused by having the wrong keyboard mapping settings active.

First go to settings > general > keyboard > keyboards and make sure you have only one language on the list there.  Remove any extras, since it is easy to accidentally activate the wrong keyboard when you are typing.

If you need to have multiple language keyboards available, then you may just need to make sure you are using the right one.  The language is usually indicated by an icon at the bottom of the screen.

Then also go to settings > general > keyboard > hardware keyboard and tap over at the right edge. Make sure that you have the correct language name of your keyboard checked.  Often there is more than one choice for a given language, and you might need to try each to see which one fits the printing on your keys.