You have two possible options:
-Create a ‘CALL FUNCTION’ event for a button/widget that calls an LVGL code (function) that sets the mode of the keyboard programmatically. See the reply by @kisvegabor here: Change keyboard mode on an event
-Or create the buttons one-by-one with a flex layout and set ‘CALL FUNCTION’ for all of them, which in turn will call corresponding functions in your LVGL-code that sets the value for the button.