CapFriendly's confirmed contract details has the contract starting in 19/20 with a European contract clause.
https://www.capfriendly.com/players/carl-johan-lerby
This lines up with what I previously understood about contracts. From what I understood you couldn't sign an UFA to a contract that starts in 20/21 yet. It also means the 1st year of his ELC will be used up playing in Sweden.
Also of note, Lerby is getting rookie max base salary and signing bonus.