Interesting.... you added lime to FFOF , and dolomite lime has calcium and mag .
Sooooo , I’m thinking your PH is dropping calcium out ... you stated you “ try your best to hit 6.5 “ .
FFOF out of the bag is 6.3 .... calcium can drop out below 6.2. If you have a PH pen , make absolute sure you are in acceptable
range of 6.5 - 6.7.
Leaves mottled with spotting will not recover , you are only trying to stymie the progression. Without calcium , plant becomes weak .
Tap water is fine under most circumstances. You can also help your plant by supplementing more FFOF as a top dress and water in.
FFOF already is prebuffered with oyster shell and perhaps your lime addition has skewed the ratio of available elements.
FFOF is a run and done soil ... MANY overthink it and screw it up by dumping other Nutes on top of it.
That soil ALONE can run your plants from start to finish , by top dressing alone.