I have a problem with adding a language-agnostic QWERTY (software) keyboard on an iPhone 4S. On my iPhone 5S and my iPad Air I have added this QWERTY keyboard which is like the regular English (US) keyboard, but which doesn't do spell checking, etc. I know I can turn off spell checking completely, but this isn't really a solution, since I use the phone to write in English, and I use the spell checker.
FYI, here is how my Keyboards screen looks on the iPhone 5S:
On the iPhone 4S, I cannot add the "QWERTY" keyboard.
EDIT: None of the devices mentioned are jailbroken.
EDIT 2: My locale is set to Slovenian (Slovenia), in case it makes any difference.