Hi there!
I haven’t yet dug into the code you shared, but it just occurs to me that have you tried the other option: break up your simulation (A) into smaller simulations (A → B+C) according to the time sections you have. By doing so one can choose/configure the isotherms in these smaller simulations one more time. Overall it will make the entire simulation look as if section dependent isotherms are used. One thing to pay attention to in this case is to pass the state vectors in a previous simulation to the next one. Please see this thread for more information (although the code is written in cadet-python rather than cadet-process).
Best,
Flynn