I see multiple things here:
Good chance the Gardin has a very different chain stay length than the Pinarello, (which is interesting as the Pinarello does not look especially long) and so a straight transfer of components may not work.
One item I do see is that in the third image the chain is in the small ring and not yet the smallest cog but the chain has quite a bit of sag, too much.
I would review getting the parallelogram more of a declining angle, which should help in sag dept. but, I think you need 4 or more additional links of chain.
The A-B adjustment modifies the parallelogram movement in relation to the axle plane, your freewheel is near that transfer point, not too tight, not too wide, you could change it, but the other items mentioned are more pressing.