I don't think it looks all that bad. Yes, some rotting roots but also some fat green healthy roots. Don't worry about one older leaf yellowing as Phalaenopsis never have more than 3 or 4 at a time anyway.
I do have Phals in moss but, I let them dry out completely before watering. That clear plastic pot is how you will tell. Dry moss is a different color than wet moss. If you see ANY wet spots, don't water. You will see an abundance of new roots in no time.
It looks like you have done well. Look at all those future flowers! Please post photos when the flowers open.
