It sounds like you haven't pulled a motorbike engine apart before. The Cota 348 is far from being an easy one.
To get that casing separated on many other bikes is straightforward. The primary drive components are removed, the shifting components are removed, the gearbox output sprocket is removed, the ignition flywheel is removed, the shift drum indexing plunger is removed. All the fasteners holding the halves together are then removed and the crankcase halves are separated.
Cota 348s have a few unusual things that can prove to be more challenging than on most other bikes.
The drive gear on the crankshaft is on a taper that can be very difficult to release.
The sprocket is on a taper that can be very difficult to release.
The gearbox components are positioned precisely left/right with shimming that can fall off the shafts during disassembly.
The crankshaft seal holders, gasket thicknesses and shimming are what positions the crankshaft in the right spot left/right and provides correct end float.