I’ve added screenshots from the simulator of how PadKeys looks on the XS Max in regular and short modes. Are you saying you would want a setting where the keyboard becomes taller than it already is in “regular” mode? (Note: we don’t have any control over the width.)
What you are saying makes sense, and would not be hard to implement. However the trick is to keep the configuration simple for the user. It starts to feel clunky when you are having to select layout and language separately.
One idea might be to have an “override layout” selector which if unset (the default) leaves behavior as now. If it IS set, that layout always takes precedence, and only the language changes when selecting by the regular mechanism.
How does this sound? It would be preferrable not to even add this one additional selector, but I cannot think of any simpler way.