What in the Wide World of Sports does this mean?
ss3 ver 08.11.09.459
I recommend to search this web for Large Level Name dictionaries phrase, it's easy to find an answer because it was discussed several times already (e.g. here is one such discussion).
Simply said, it's just an information the design file containts a lot of level definitions in the internal dictionary, which can slow down MicroStation. It's recommended to compress the design file to remove unused level definitions.
Labyrinth Technology | dev.notes() | cad.point
you mentioned several different issues (some from them I don't believe are related to level the large dictionary issue at all). In my opinion a correct way is to create new separate posts for every issue and to not extend this one, which was only about what "large levelname dictionary" means.