I nearly fell off my chair to encounter DL’s use of “pretty”! This idiomatic expression is widely used when spoken, (less written), in Australia but its use here is astounding, and potentially very confusing. It is common to hear: “I’m pretty good” [I’m well”]; “Things are pretty bad!”, [We are having a ‘run’ of bad luck: ill health, debts; death in family]; “Pretty soon”, [ An occasion happening fairly soon; usually weeks or within a year); “She/He/It has taken “pretty bad”, [She/He/It has become seriously ill and may not recover] “Pretty bad”, [understating something or someone is awful or horrible]; “She/It’s pretty”, [She is pretty, lovely, good-looking] “What a pretty baby”, The baby is beautiful or "pretty". People or things may be arranged or dressed “prettily”. Generally meaning lovely or attractive, but also: colloquially the meaning here is close to “rather” or “quite”.
"It is very interesting" is offered as an answer but my "It is somewhat interesting" was not accepted.
There is a famous book by Damon Runyon (1930's I think) called "More than Somwhat". Perhaps this could be translated "Piu di piuttosto"?
Edit Thanks to siebolt, 'Piu di un po' it shall be. But Duolingo just emailed me that they now accept "It's somewhat interesting". This shows that when users raise flags they are certainly noticed which is encouraging.