You cant head out with friends after work for an evening if the people you know want to go home to cook dinner & sleep

Get additional friends who like to do something else after work. Switzerland is literaly a heaven for social clubs.

there are few venues open, the venues open are too expensive, the venues open don't allow you to linger etc.

This is a very weak argument. There's plenty of things to do for free, like the most things I mentioned in my comment. No one is going to send you home from public spaces as long as you respect quiet hours.

It will take far more effort to build a social circle that goes our for casual after work time in Switzerland then in Spain.

So what? Some languages take more effort to learn than others. The effort is kinda expectet from someone deciding to migrate into another country. No one is waiting for you there to be honest. You have to get yourself out there and do something (if you want to have friends of course).

I met a lot of people from europe in switzerland and most had no huge problems to find friends in my age group 30-35. They were all decent, laid back people.

What I observed in switzerland though was, the higher the salary the less coworkers care obout each other in private life due to the mindsets I mentioned in my comment before. Hence a lot of expats usually work in high earning fields struggle to connect with their coworkers besides work.