I decided to give this one a go as a custom miscellaneous magic item (specifically as a wondrous item) using the content editor. If anyone's interested, I did all the heavy lifting in a single eval script:
doneif (field[gIsEquip].value = 0)
~ +4 insight bonus on all Wisdom saving throws
#applybonus[BonInsight, hero.child[svWill], 4]
~ +4 insight bonus on all Perform & Craft checks
foreach pick in hero from BaseSkill where "Helper.SkCatPerf | Helper.SkCatCraft"
#applybonus[BonInsight, eachpick, 4]
nexteach
~ A Bard also gains additional bardic performance/day equal to his nymph muse's Charisma modifier (in this case +7, as nymph has a 25 CHA)
#trkmax[cBrdPerfor] += 7
Finally, I'm not an expert on this, so if anyone sees any errors or potential optimizations, please let me know.
Thanks!