That is great progress. Keep bringing them treats and whispering sweet nothings. Every flock I've had has some birds that are slow to warm up while others are right there pecking at me until I pick them up. Some birds took 6 months to fully appreciate my company. Pay attention to the pecking order and always pick up the top bird(s) first. Then, look your shy hen in the eye, say her name sweetly and hold your hands out. If she runs away, tell her that's ok. If she squats and holds her wings out, gently pick her up under the belly. Hold her for a minute, pet her and gently put her back down. I think the shy birds learn from watching it's fun to get attention and a cuddle. Don't neglect the shy ones, even if you say their name and greet them everyday they will learn to trust you over time.