Learn Swedish: Inte ens juryn buade åt fiaskot. - Not even the judges booed at the fiasco.

Inte ens is a focus particle directly modifying the noun that follows it (juryn). Because they form a single grammatical block together, Inte ens juryn counts as the first position in the sentence (the subject phrase). Therefore, the verb buade correctly sits in the second position.

Could I put inte ens later in the sentence, like Juryn buade inte ens åt fiaskot?

You can, but it changes the meaning. If you say Juryn buade inte ens, the particle modifies the verb phrase, meaning 'The jury did not even boo' (perhaps they just sat in silence). In our sentence, placing it right before juryn focuses it on the subject: 'Not even the jury booed' (nobody else did, and the jury did not either).

Why is the preposition åt used here instead of på?

The verb bua (to boo) almost always pairs with åt to indicate who or what is receiving the negative reaction. This is a common pattern in Swedish for verbs expressing an emotional reaction directed at someone or something, just like skratta åt (to laugh at) or le åt (to smile at).

Is juryn a regular Swedish noun? It looks like an English loanword.