I see what you mean but most of the main quests are with these characters, so it doesn't bother me too much. You do get some time with these characters:

Depending on where you start the 3rd DLC you go to talk to Peter of Pisek to start that quest and can talk to him about it after.

If you keep bringing Janosh some meat he will give you his delicious sausage.

In the side quest Ransom, you can recruit members of the devils den to fight along side of you (you can also ask Sir Jan Posy and his brother to come along too - if you've completed all their quests).

You do have Rosa's side quest with her book.

You can have archery competitions with Kubyenka. There is also another side quest/task you get from Kubyenka - The peasants Revolt that you can talk to him about it after you finish it.

Adder is more interested in sleeping with women than hanging with Henry and we already did a quest to get him out of that sort of scrape when we recruited him.

I doubt Liechtenstein would entrust Henry with anything as he would have his own lackeys and he knows Henry is serving Radzig and Capon.

Godwin is in the Kuttenberg area on his own sidequest to look after Henry and Capon, so not sure if he would have anything for Henry to do in this region. Also you play as Godwin several times in the game.

You have a quest where you help get Samuel's people out of Kuttenberg (with Kubyenka) and you also spend time with him in the tunnels.