HaloMods "Classic" Read-only Archive

Forgive my extreme ignorance, but why can't user-created Halo CE maps be opened in Spark Edit?

And, what program CAN I use on CE maps that is similar to Sparkedit, if such a program exists?

Thanks

Sparkedit doesnt work with HaloCE. Gren could make a new one. But meh
Theres no program like it other than Sapien