So did repotting help or is that one plant still yellowing off?
Been growing in organic soil for years and have not checked the ph of anything even once. Don’t overthink it. Every time plants begin to yellow I just repot to fresh mix with added compost & it usually corrects whatever is wrong. In this case it could simply be a lack of minerals/macronutrients that assist with absorption like calcium. Adding organic material like compost, base soil, and mineral inputs to the root zone typically drops the ph a bit more acidic. You would also need a decent soil ph probe to accurately measure it. I don’t have one but don’t really need it either. The plants tell you if something is off.
Hydrated lime or epsom salt as stated above is a last resort but bubbling a few tsp either one in water for an hour or so could help...just not mixed in a tea. If you are not giving calmag like gen organics cal mag plus that could be at the heart of the issue. It’s actually kind of hard to provide cal-mag in a soluble form without it coming from a bottle. Add in some D-lime and/or crushed oyster shell and/or garden gypsum when you recycle the soil for next run. Composted eggshell is another good source of calcium but as a side note.. takes a real long time for them to break down; use a soluble cal/mag until then to assist with absorption. Finally if you are not sprinkling granular mycorrhizae in the hole at each transplant your plants could be missing out on the benefit of symbiosis with fungi which assists with the absorption of all the nutrients present in a given mix. Once your mix reaches the coveted supernatural status absorption and/or ph issues no longer surface.