You will see more than enough to buy the three beers !

EC 261/2004 downgrade refund (not compensation) is 75% of the base segment fare in F. Not the fare difference to J, but of the F fare. That may wind up being a significant amount of money.

As it stands, you are scheduled to arrive at your final ticketed destination of BKK earlier than originally scheduled, so no delay compensation. Had you voluntarily routed through FRA and thus delayed into BKK, that would not be compensible. So, in the end you do quite well.