They fixed that with Mountain Lilly tho and they had 100% after the second day or so. Not sure to be honest... the shop says they up the skill or equipment level by 1 with no mention of a chance like other skill blooms have.
An interesting note as well... all the 'lily's or at least those with lily after their names love books. Mountain Lily, Toad Lily, Water Lily and now Star Lily.
EDIT: Actually now that I look at the other skillblooms they say 100% chance of upping the skill for that * level. So I would say with almost certain belief that they will be 100% for this event as well.