One issue is how the standard applies to different languages. A2 in French is enough to get by around Brussels, but B1 in Dutch is barely enough to understand people where I live now (dialects are to blame as well, of course).
Familiarity with one Latin-based language means other Latin-based languages “sound understandable”. I’ve no other connection to make with Dutch. But okay, that’s just personal experience.
However, it does seem that this Swedish party is willing to "repatriate" even Swedish-born citizens, so at least they're consistent.
You wouldn't expect your child to be Pakistani if you get birth over there as 2 German individuals.
What you said makes no sense. Vanishingly few liberals believe laws should apply equally to citizens and non-citizens. If they did, they'd be for the complete abolition of visa/residency conditions altogether, simply allowing anyone to immigrate to the country. I doubt that even in the US more than 5% of people believe this. Any European country it'll be <3%.
Any visa/residency condition is a demand not imposed on citizens. Language and cultural assimilation aren't any different from other such conditions.