"What's silly about this?

In fernem Land

libretto"

The endless "hail this, hail that", the pompous talk about Germany, that bit where everyone can't get over "The swan..." etc etc etc

Silliness is, de facto, a relative thing in opera, I'll give you that. In order to listen to opera, you do of course have to get past the fact that people will be singing often banal words, exposition etc, and giving them a projection that gives them a bathos that is inherently silly.
("how are you to-daaaaaaaaaaayy?" "Can't complain maaaaaaaaate!" "Thank you very muuuuuuuuch" "you-oo-oo-oo are most wwwwwwwelcome!" - I'm exaggerating for caricature, but not much).

But the stuff you linked to summarises in a nutshell precisely the sort of pompous silliness that characterises that opera for me. It's straight out of Monty Python.