From all I’ve having lived in a couple of countries in the EU (including the UK), exposure to Proportional Vote in the EU Parliament Election seems to have zero impact on people wanting it for other election, maybe because EU MPs are too far away from most people and don’t really get all that much news coverage, unlike the national politics of a country.

Mind you, personally exposure to Proportional Vote when I was living in The Netherlands has definitely made my mind in favour of it, especially after I moved to Britain and was exposed to their shit-show FPTP voting system (worse than my own country of Portugal which as multi-representant electoral circles, so way less Democratic than PR but nowhere as bad as FPTP).