Why are you not using "issi" ?
Because ēdrusi mean "are sleeping" so you don't put issi.
Because 'Riña taobā ēdrusi issi' would be translated into 'The girl and the boy are sleeping they are'. Unless you're doing a yoda parody in High Valyrian, I wouldn't recommend writing it like that.
Why "Rina SE Taoba edrusi" doesnt work ?