We will create a battery bundle with the values we want by connecting 2 batteries in series. We do not want the energy transfer between these serially connected batteries to be equal, and we do not want one to flow into the system more than the other. We do not want any short circuit events to occur. What kind of a PCB circuit can be created for this or would it be appropriate to use a diode?
This has neither to do with batteries nor whether they are connected in series or parallel. This is referenced to the load .. but you don´t speak about load and load conditions.
If you want to occur short circuits, then train the personal. But if you want to protect your circuit in case of short circuit, you obviously need a short circuit protection. In simplest case a fuse. Done billion times.
If you don´t want to use a fuse, then tell wha, and tell how you want it to operate. Current-time behaviour. Latching or non latching ... if latching, how do you want it to be reset? And so on. It´s your idea, so don´t hide your ideas ....
The ultimate guide to understanding what battery equalization and equalizer is, balancing the battery with an additional balancing device for your solar