Might we add to the Attribute Manager (then roll the whole thing into the layer dialog):
1. Send elements on deleted layers to the ArchiCAD layer, or prompt the user for a layer for this purpose.
2. Merge a layer into another. When you merge data from an old project, sometimes standards have changed and you end up with two layers of nearly the same name and exactly the same function, causing confusion going forward.
3. Stop reporting that a layer is in use when it is merely currently set in a tool default. Or differentiate these uses.