I've managed to download the Ayakashi Rumble collab characters with the default 2_build_rpy and 3_write_config DMM files. I've installed the Nutaku player, but I'm still downloading the assets.
Edit: I didn't have any problems with the Nutaku player's 2_build_rpy, [Commander of the Dusk] Yamaraja works for me with the default file: . I've gotten the Machine Beast eidolons to work on the Nutaku player by changing the highlighted code in 3_write_config, the right one is the new one: .