So I was going through organizing the song book of a new bard I made after using the level 100 heroic upgrade and I found that for some reason the level 57 song "Soothing Psalm of the Sunrise" was not included. I also tried the clicking on the spell gem to assign the song slot that way in case I was just overlooking it and it isn't in the song book.
Probably because it's a Lceanium spell (EoK expansion). Several classes got spells in EoK that were earlier that the EoK expansion levels (101-105). Did the bard get Selo's Accelerato (66th level song)? This is another EoK earlier spell/song for Bards. If you got that one, then Soothing missing is probably an oversight. If not, then it's probably the case that none of the Lceanium spells are given out to 100 heroics.