You don't really need bitmap files of the foreign characters.
In Freebasic I did, since there was only one type and size of built-in font.

I'd further suggest you do the translation based on virtual key codes rather than character codes, making it independent from the host system's locale-dependent keyboard layout.
I'm not sure how to do that, right now I tested using KeyEventArgs->KeyCode. I didn't figure out how to globally detect the KeyDown event, so I'll create a function and have all the textbox's KeyDown events go there. The function will recieve the KeyEventArgs and the textbox's Text pointer, along with language specifications. The function will evaluate a one-character string based on the language, add it to the Text received as a parameter, and also set the KeyEventArgs Handled to true. So far what I tested, this seemed to be working fine, although I didn't try it out yet on my program, only in a small test-program. No more QWERTZ german keyboard! :P

And I'd still suggest to provide a virtual keyboard, as an alternative to the physical one but at least as a visual display of the foreign keybord layout.
Or... I can do what I did in my earlier version. That is, give the user the ability to change the virtual keyboard for each language. So for each character, the user presses a key-combination he/she wishes to use, and the KeyCode is stored along with whether shift, control, and alt were pressed or not. That'll provide a few hundred possibilities... And, I don't know about you, but I first like to have the program completely working. After that will I concentrate on things such as adding a visual display, help, and other things.

Experience shows that out of the programs I write, those I regularly use myself gradually improve in usability over time, eventually usually becoming the better ones.
Oh, this program has a lot of history. The first version I wrote in QBasic in 7th grade for spanish class, all the words and meanings were hard-coded into the program, with the only "option" being whether to ask them randomly or not!