There were two questions in your post.
The reserved attributes are mainly for 4DWP documents, but you may want to use some inside “sub-objects” inside documents too (right ?)
The list of reserved attributes exists, but the list may change in the future.
So rather than trying “not” to use reserved attribute, use attributes with an “" character in their names.
(4DWP will “never” use any "” in attributes names)
Use a single object : my_private_attribute
or use as many attributes as you want