I found a workaround, not sure how solid it will be for the project behind:
a) during the first 29 frames I process any character coming from the key buffer, I enter the status "KEY_PRESS" and "KEY_DOWN"
b) after 30 frames I check if the key-character is in the buffer, so I keep the status "KEY_DOWN" if its not in the buffer we are in the state "KEY_RELEASED"
c) after 30 frames I check every 7th frame if the character is in the key buffer and stay in "KEY_DOWN" status or if not change to "KEY_RELEASED"
Example over here: https://fuzearena.com/forum/topic/947/re-use-sounds-from-the-soundfx-generator-with-the-usb-keyboard

🙀 Excuse me, I understand now the box is create on the text