Conservative - comfortable, not pushing any boundaries
2: 'ever to grace the earth' is OK. 'The dinosaurs were the largest land animals ever to roam the earth.' (They haven't done it for 65M years, but the present tense is still acceptable.)
However, in your context, 'graceD' is also possible - though not in your first version. Another possibility is "She will never be forgotten as one of the greatest voices ever to have graced the earth." (I slightly prefer this to your second version - as the infinitive makes the value judgement less assertive than a bald finite: 'it HAS graced the earth'. But that's just me: your version is perfectly acceptable.
Student or Learner