When doing challenges like these dear Ilvermornian, all the knowledge you could recall would help you figure out the riddle one way or another. Limited or not, you are definitely on the right path.

Wood scratched against wood as you stood up from your seat, sending a good amount of dust to fly around. Not that it mattered now, because you’re on the right track, my dear. Remember that the piano is as old as this shack, so please be careful in opening that lid.

And while you’re at it, why don’t we give the riddle another go. It should help you figure out what you’re exactly looking for.

One is held dear to our pigletted friends.
It can’t build a home, but a house it does amend
To every boy and girl cherished at the castle,
But you won’t find it without much hassle.

What could possibly be so important to our pigletted friends? To every boy and girl cherished at the castle.

At the castle. Hmm. Perhaps, now is a good time to refresh your facts and figures on Magical History once more...or perhaps for you dear Ilvermornian, your stock knowledge about wizarding history would come in handy right about now.