Slam Creepers were a rock band from Vansbro, Sweden formed by Björn Skifs in 1962 and broke up in 1969. Björn Skifs then went on a solo career. They had some moderate hits including a cover of a Foundations song "We Are Happy People". Skifs would later find success with a number 1 hit "Hooked on a Feeling as a member of Blue Swede.
The rock band Slam Creepers had some highly successful hits
Given the context, the scenario only stated they had some moderate hits but did not go into too much detail about if that was only in their country or not. The model probably got confused because the next line states that the band founder made a number one hit as a member of a new band.