During the first moments after the announcement, euphoria ran through the Spanish Sailor Moon community and very interesting things were said.
The person who has been responsible for the translation and adaptation of the films commented that there would be certain nods to the Spanish dubbing of the 90s but that many other things were imposed or were rejected by Naoko Takeuchi herself, who was also supervising the adaptations to all the languages. We can confirm that she has been more involved than with the rest of Crystal.
I wouldn't be surprised if this was part of Naoko/Toei's new rule, where the original Japanese names (Usagi, Ami, Rei, etc.) remain untranslated or altered, if "Mamo-chan" is left alone in EVERY language dub.
It's pretty obvious this Mamo-chan stuff is coming from Naoko. Toei couldn't care less about a nickname used in the show.
Before Naoko entered the scene, Toei was giving permission for both the European Portuguese and Latin Spanish dubs of Crystal reuse their old character names.