Sweden was a minor power with less than 6,5 million inhabitants half a world away, with little interest in either Japan nor China, militarily and economically.

Sweden was an early and enthusiastic participator in the Legue of Nations. The Swedish envoy to the Legue of Nations was Fredrik Ramel, a career diplomat with a short spurt on the position 1929-1932 (during the short-lived right-wing government that won the so-called 'Cossack Election 1928). He favoured using military force to uphold international agreements and tried to coax the Swedish social democrats out of their isolationist and pacifist stances at the time, with little success.

Rickard Sandler replaced him when the social democrats won the elections 1932. Sandler was an internationalist and in strong favour of a Nordic defence alliance.

Sweden at the time was in the early shocks of the depression and large-scale clashes between organised labour (unions) and employers, that culminated in the Ådalen shootings 1931. In general, Sweden's eyes were fixated on internal matters at the time.

As far as I know, however I have not been able to secure any sources to substantiate that claim, Sweden voted for the call for Japan to cease military operations 1931 and the branding of Japan as the aggressor 1933.