That’s entirely up to you. Those bottom leaves may never “heal”. If it were my plant I’d say fk it, strip the unhealthy growth and push on knowing I had a few more cooking that we’re doing well, but here comes the disclaimer, You “probably” shouldn’t be training an auto. Most folks tend to agree that autos should not be trained or topped much ect as they have a predetermined lifecycle and won’t have the time to heal properly. The yield tends to suffer and the plant never reaches full potential yada yada
If This is an auto as mentioned and since it doesn’t have much time to recover from a lot of stress especially since you’re already flowering I would leave it to do it’s thing. You’re probably best served leaving it alone either way as if there is something really wrong you tend to see the affects in the Leaves first. I would recommend monitoring the run off for ppm and ph and adjusting feed accordingly based on those results. Once those leaves brown/crispy and the life’s been used up by the plant then yank them.
Your runoff/ppm can tell you a lot about what’s going on in the medium. I tend to take weekly readings in veg and flower. One a week in veg and twice a week in flower. Imo you did the right thing here which was flush it with ole natural water ph’d. This typically fixes any nutrient build ups you may have in your soil. The stains on the side are simply nutrient strains and they’ll come and go as you water or feed (more severe in low air flow environments). Not sure what your watering schedule is like, but my flowering plants in 5lb fabric pots require watering every 2-3 days. Some folks prefer the old school knuckle test rather than a set schedule. To do so, stick your finger into the soil, if its dry on the tip to the first knuckle it needs water. You could also opt to lift the bag and if it’s light it needs watering.
You have roughly the same size tent I’m using for flower. It’s too small for 4 plants in flower. I use the space the 4th plant would be for an oscillating fan and a small dehumidifier (flower) or humidifier (veg). The air flow or lack of at the bottom very well could be what’s causing your fuzzies. Might be helpful to get a full shot of your tent when you get a minute. Also happy that you got these plants through their rough spot , stuck it out and will have a harvest, well done.