I'm currently writing an immediate mode gui library just like this one for a specific purpose and I found your library is a great ressource for ideas on how to go about it.
I took a closer look at how you handle forwarded keypresses and found, that it simply sets the given input and hand it over to the widgets. I haven't tested this with suit, but in my plain love2d tests, i found that keypressed and all other events are likely to be pressed multiple times (1-2, textinput got 8 when smashing my keyboard) per frame, so I would guess you are likely to miss events when processing them inside.