Couldn't you in fact make the opposite case?

Sweden as the outlier is not reporting accurately and others are?

The UK has seen huge excess mortality above the average which is being attributed to large numbers of undiagnosed deaths in care homes and in the community.

Its far too early to make any claims as to superior accuracy when almost every country is struggling with accurate testing across their entire population.

In which case you'd expect Swedens numbers to get revised strongly upwards.

Sweden also has no conclusive sign of flattening yet.