The 23-year-old joined Hearts from second-tier side Mighty Jets last season, becoming an instant hit.
He ended the season as the club's topscorer with 11 goals in 21 appearances.
“I am very worried with the goal drought. It is disturbing, especially after enjoying a very wonderful run last season. I was hoping to replicate that form this term but it hasn’t been as hoped after eight games,” Cosmos told Class FM.
"Right now, I'm facing a lot of challenges preventing me from scoring consistently due to the persistent injuries. After just a goal, I have suffered a drought.
“Although, I know the situation is another phase of football, I am worried but I have to be calm. I am mentally strong and treating the challenge with a positive attitude.
“Very soon, I will hit full fitness and the supporters will feel my presence because the season is still young,” he added.
Hearts are currently sitting sixth on the log with 12 points and will travel to Golden City Park when the league resumes on April 1.