You can think of a library like the wheel - it's code that is useful enough to be used in multiple applications but would be unnecessary/painful to re-invent every time you needed it.
Harven does use his own settings panel library rather than the fairly universal LibAddonMenu. If I remember correctly, someone posted an unofficial update to Harven's settings library on the forums but I'm on mobile and can't find it at the moment.
edit: Garkin's compatibility tool may fix some things, but if the error is related to Harven's settings, I don't think it will help.
edit 2: I had a feeling it was Garkin that provided the update for Harven's settings
https://www.dropbox.com/sh/tedcy6ima...date5.zip?dl=0