I’ve solved the flashing issue by utilizing the functions .lineColor, .lineWidth, .opacity in Begin Routine, and setting .setAutoDraw(false) and the variables that I use as parameters in the components themselves back to their original values in End Routine.
I am now encountering the issue described here: Textbox2 unexpectedly reset its text in the center in PsychJS (fine in PsychoPy) - #4 by wakecarter, where I am changing the color of the words in the textboxes when a specific key is pressed, updated every frame.
Upon a key press, the text in the textboxes flick to the center of the screen for one frame while changing color, before returning to their correct locations. Is there currently a fix/workaround for this?