So long as it drives ok it will be fine, ecu links fuel with boost ir if it does not see any or small amount only a small amount of fuel will be added.
Unleaded cannot cause this, long term seat erosion on hard driven ones is a disticnt possibility, so as you I would check particulalrly the actuator.
Make sure your dad knows you don't blame him, you only get one dad, and it no doubt be making him feel bad as well.
My dad won't even drive my stg1, prefers his v8 xr4i as totally different power delivery, and not so "MENTAL" to use his words!!
He said it "didn't go that well", until he hit the boost in second!!
tabetha