About Mania key count conversion mods

[SevenChords]

I noticed today that the key count conversion mods for Mania only apply to beatmaps that got converted from Standard to Mania, not to beatmaps that were made as mania beatmaps.
I was wondering if this is intentional, or if the keycount conversion for Mania first beatmaps is just not yet implemented, after stumbling upon a ranked 18k beatmap that i tried to convert to 9k with the 9k mod (as i am currently not skilled enough to read/play 18k beatmaps).

[Newbie1st]

It's always been restricted to converted maps, most likely this would require a completely new separate algorithm for the dedicated mania beatmaps.