A general question: Import21.lsp and Import21.wal - Why should I edit these files?

When Ease imports an Ease 2.1 Project, Catalog.lsp or Catalog.wal, it creates or updates the so-called import books Import21.* . These files hold the names, labels and locations of all formerly imported Speaker Models and Wall Materials. In consequence this list will be used when you start an import procedure and you choose Global Base import. In this case all Speaker Models and Wall Materials already imported (with the same label) won't be imported again. Editing this file allows you to remove several base files from the list. If you do so, they will be reimported during the next import procedure. (Base files shipping with Ease 3.0 on the CD are registered as already imported during the installation.)
Generally spoken, Import21.lsp and Import21.wal tell the program which Speaker Models and Wall Materials should be considered as already imported.

Please keep in mind: Self-imported Speaker Models are not authorized. Because the frequency and angular resolution is higher, the manufacturer may have decided to add some more detailed data, so that the old Speaker Models are no more valid.
See also question below.