As long as he is eating the dry food there is no need to worry about the fresh at all as it is a complete and balanced diet.
At this age he is now a settled hamster who will have set himself a routine that suits him. Perhaps you are expecting to much of him in terms of him actively seeking your company? Hamsters are hamsters and they do hamstery things. They are curious and just want to run about and investigate. Once he is older he may enjoy sitting more with you but he is still very young just now.
Personally we really don't like balls. To us the animal is going nowhere as it is just in the same place. It cannot sniff, climb, dig, chew and investigate anything as it is stuck in the plastic sphere.
I would go with the bed idea but he won't sit still there either
We use the duvet and pillows and make tunnels and lumps to climb on. They seem to enjoy this but you can never tire a hamster out as they are very active.
That said though if he is constantly lethergic then you need to give him a full check over. He may have some illness brewing or have a sore bit like a leg or teeth problems.
Can you weigh him to make sure he is either growing or maintaining his weight? I would expect a youngster his age to still be growing and maybe put on a few grams a week till he is 6 months or so.
Don't overdo the treats as they get bored with them. Most of ours wont eat them outside the cage so that is not unusual.
I would take the roof off and get him out when it suits you. They soon learn to wake and and come out when you want. I don't mean a lot during the day of course but evening is fine to wake them as they can always go back to bed can't they.
Hope he is OK.
He is what he is and has his own unique and special and very beautiful character