When I press a multi-character chord and the text is filling out, if I press another button/chord it is ignored instead of being added to a buffer. It would be great if I could keep typing while longer MMCs fill out.
However, an exception to this are the mouse buttons. I've mapped the middle mouse button to be my space character, because it is really fast to press that button. However, if I hit this button while an MCC is filling out it will insert a space in the middle of the MMC. This is jarring, requiring me to delete text.