Sorry to ask but can you define "customize mapping" ?
(in my mind they are all custom as starting from a empty file, so trying to figure out exactly what you look for)
PS: https://www.youtube.com/watch?v=5CgBmj7Jz6Y&feature=youtu.be&t=18s will help in getting better answers
Assuming you mean BI Apps customised files? Unfortunately it's not easy to identify them as other processes stamp the last update date and last updated by fields.
Reference to customized leads me to believe that you have a pre-built solution of some sort ... Using a prescribed customization scheme allows you to quickly identify customized items. If you didn't do that, then perhaps you can do a 'diff' on the vanilla pre-built versus what you have currently.