OCIO source setup in depth explanation

Hello,
I’m not a fulltime pipeline developer but I’m trying to improve my python skills in vfx and shotgun/rv. My latest nemesis is setting up an automated RV pipeline with a custom ACES Ocio config.
I already worked myself through the OCIO source setuop sample package and so far everything is working fine. I’m able to load the right ocio.config dependant on the file I’m loading. I can also setup the file transform/look and display so that everything works fine.
What didn’t perfectly work for me was that RV automaticly set’s these groups depending on the file I put in.
I already checked this post:

but I still have problems. I usually end up with a correct load of the OCIO but not a working file transform / display activation.
So I tried the “btl_ocio_source_setup.py” that “mmoshev” posted 2 years ago… (lots of love, helped me a lot already!!) …
With this I managed that RV set’s everything automaticly and in the right way. Unfortunatly if I use this way I’m running into 2 new problems.
First of all I’m not able to disable the file transform or display transform once I’ve loaded a file. It’s not locked or anything but trying to turn it of nothing happends.
The second problem is that it seems that the “output” doesn’t seem to update when I loaded multiple files. I start by opening a “sRGB” jpg and RV works correct by setting the file transform to “output srgb” (so that the file get’s linearized, right?) and the display to “sRGB”. All good so far. If I now load in an exr the file transform is set right but it seems like the viewer is not updating so the exr looks wrong.
Sorry I know this is very basic stuff but I can’t find a very detailed explanation of the source setup and how exactly it works.