I checked it out and indeed, Zircon maps open in Crystal Map Editor. Last time I really looked at Zircon was when it was released and I mistakenly thought that its maps also have .zl extension, not just the libraries.
I take it then, your new map editor only works with .zl libraries.
If Zircon .zl libraries have the same tiles in them as mir3 .lib ones in m2 Crystal client, it opens a way to use some features of your new map editor built for Zircon that mir2 map editor doesn't have (or you implemented some features better) when working on mir3 maps. Those maps can then be used in mir2 client.
Now if Zircon also had all mir2 libraries in its .zl format, your editor could be used where the crystal editor comes up short.
Is there a library editor for Zircon *.zl libraries that can export/import bmp tiles? If yes, then mir2 *.lib tiles could be exported and in turn imported into .zl libraries and voila, you could edit mir2 maps in your Zircon editor.
And how it is with objects in your Zircon map editor? Can those be used by Crystal map editor? I suppose I could look it up but might as well ask.