I don’t think you need to change the name of our Master Aperture Library to suit Lr.  The name of the folder is irrelevant; all the Lr catalogue needs to know is where the photos inside of it reside.  On my external HD I have a single folder My Photos and within that I have a folders: iPhoto Library 1996-2009, and yearly folders.  I started using Aperture in later 2009 and managed my Aperture pictures by year and eventually converted them to referenced files on an external HD, keeping the year folder format.  Now all new photos go exclusively into Lr using the year folder format starting with “2015.”  So In Lr Folders, these folder titles remain the same.  Now if you really want to change the name of your Aperture Masters you NEED to do it within Lr and NOT Finder.  Right click on the folder name and select “Rename” from the dropdown menu and Lr with automatically change it in Finder. However, if you plan ensuing Aperture, Aperture will probably not be able to find these pictures because of the folder name change.  That’s why I left things the same and didn’t worry about the name.

I have vaults on several smaller portable HDs and have left them there so I do not know what to do about the vaults.  If you are keeping Aperture for now then I’d probably keep the vaults as well.  Hope this helps.

Florian