I have been making a very low resolution game, I mean it to look like a 90s or 80s game, but because of its low resolution (just a little smaller than a GP2x screen) I can't make the filled region small enough! Is there anything that can be done?
Use something else than filled region. For example, you can just create a simple box in ms paint that has the dimensions you need. Then just add an actor with that animation and set its VisibilityState to "Don't draw, but allow events". There you have an actor acting just the same as a filled region actor of that size.