I think you are a bit too harsh about the Swedish Landsverk tanks. At the time of their design, they were easily a match for contemporary German designs. Only by the time they had been ordered and produced in sufficient numbers, newer models of tanks had overtaken these designs.
Point in case would be the L60 light tank. It was designed in 1934 when Germany had no armoured forced to speak of. For its time it was very modern. Had the improved model been ordered in large numbers, tank production would really have come off the ground by the time the war started and the follow-up models like the Lago could have been built earlier and in sufficient numbers too.
So, in the case of the Swedish tanks it was more a case of too little too late than really a design quality problem.