Hi, and welcome!
Sadly I don't 'know' the answer, but I'd suspect it hasn't made a huge difference if the PH was 5.3, and I'd guess that the beer will be absolutely fine. At least its not going to be a problem next time!
Maybe with this small bump someone else, with rather more knowledge than myself about water chemistry, could hazard a guess?
Cheers
Kev
CRS cleaned limescale from element