From what you say, I imagine that the main distribution board would be on the other side of the wall. The connection points for the inverter and the generation system on the electrical installation are aspects that require attention. Errors that create a risk of overcurrent due to multiple sources (Enedis, PV system, storage) are often seen. Connecting to a sub-distribution board makes this more complex. Ideally, the storage system should be connected to a source interconnection board upstream of the main distribution board.
From what I have often read (particularly in this thread), the JK BMS is wired in the same way as Pylontech batteries, using a type A cable. The VE.Can port must also be configured with the CAN-bus BMS (500 kbit/s) profile.
The Enphase gateway is not connected using a USB/MK3 cable. It can be integrated via Modbus TCP, or a meter connected via RS485 or Ethernet can be installed. It can also be integrated via Node-RED as a virtual meter, but that is not the simplest option. Ultimately, integrating the PV generation system is not essential for ESS to operate.