Her songs were also featured in compilations of English song

1. in which引导的当然是非限制性定语从句.
其中：(in which) her credit was not always given
= her credit was not always given (in which)
= her credit was not always given (in complications)
2. 翻译：她的歌曲在那些为英语语言专业学生（所听）的英语歌曲汇编中也颇引人注目,（不过）其中给她的不都是赞誉.
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团长答的是对的！

in which 是作为非限制性定语从句安排在这里的，其先行词是 songs。便于了解句子的安排细节，不妨将定语从句写为另一句：
Her songs were also featured in compilations of English songs for students of the English language. In these songs, her credit was ...