The exploit made him the first player since Diego Forlan in 2005 to register a league treble against the Blaugrana.
“I have watched some of his matches and indeed he is a very good player,” Appiah told Ghanaweb.
“He showed it when they played against Barcelona because it’s not every youngster who has that character or that confidence to play against Barcelona and score three goals.
“I think that now he has the chance to play for the national team, so I’m wishing him good luck and I know he will do well.”
Boateng, who ended the season with six goals in 25 league matches involving 10 starts, made a transfer to Levante last summer in a four-year deal from Portuguese side Moreirense.
He initially joined Rio Ave in 2013 before moving to Moreirense in 2015.
The Accra-born represented Ghana at the 2015 Fifa Under-20 World Cup in New Zealand, where he netted the solitary goal in a 1-0 triumph over Panama.