I had some yellowing like you did earlier and thought it was probably N deficiency. I am the same way not wanting to stress tranplanted seedlings with too much nutrients. However, I dilute the N rich foo like 10x less than the direction of my orchid feed and water it, the plants recovered very nicely. I normally use bloodmeal and bonemeal to prepare the soil before transplanting plus worm casting and compost I make. Blood meal gives N and bonemeal has K & P. There’s stuff you can water to help with transplant shock like kelp, fish emulsion and Vitamin B
As precaution to prevent bugs to set in, I also make organic spray, you can check it out here Safe, effective, organic homemade pesticides - #3 by Ning.
I would spray before even seeing any bug as garlic & chili deter them and I spray my plants ane veggies with it at least once a week, if I’m lazy.