So I just transferred from Astroberry to Stellarmate the biggest issue I have is restriction.
I have Svbony 705 on SkyMax127 and custom 213/50 guidescope with LibCamera all ran by OnStep

In astroberry If I wanted to image anyhting or platesolve with guidecamera(Libcamera) I just pick libcamera and it works. In new versions of Indi and so in stellarmate I have this thing "Optical Train" which is not bad it auto-selects focuser, scope it is connected to and so on.

Now I am not allowed to select guidecamera. Even my train that has no primary camera just guidecam does not allow me. While solution is sort of simple - add a new train with guide camera as "primary" it gets cluttered pretty fast especialy as I do not have any idea were to rename Optical trains, so now I have Primary and New Train New Train(1) New Train(2) New Train(3) New Train(4) New Train(5) - due to 2 primary scopes 2 guidescopes, and 4 cameras

This is just annoyance it is not u bug but a thing to think about and maybe improve user experience.

I probably am mis-understanding your issue. Is it simply, that in the new way, you create a train for your primary camera, and then create a train for your secondary camera e.g. your guide camera (which you can rename from Secondary to Guide, if you want to). Then you choose the primary train for your main imaging, and the secondary (Guide) train for your guiding. If they are setup correctly, that's all you have to do. (the primary train definition makes no reference to your guide camera. There are links somewhere on here for how it's setup)

Ok, I think ai got this now, it does make more sense when you count in focusers and filter wheels. Also my additional issue was with my guide camera crashing and that is why I was not able to select other train.