A prominent line of inquiry has focused on the association between types of electoral institutions and unidimensional congruence between citizens and legislators from a comparative perspective. However, it is less clear what our expectations are if congruence is assessed (i) in a multidimensional space at (ii) varying levels of proportionality within a single political entity, such as in the elections to the European Parliament. I argue that more proportionality is associated with more congruence, but this is less a consequence of spatial incentives than of vote-seat conversion effects. Using a novel measure for multidimensional congruence---Hutchinsonian hypervolumes---, I find empirical support for this assumption based on the EP elections of 2009, 2014, and 2019. Furthermore, higher levels of legislative congruence at a national level are associated with higher levels of trust towards the EU at an individual level, indicating that representational mismatches matter for support for the EU more generally.