In my experience, mapepo is translated as spirits and mashetani as demons
Agreed. Mapepo means ghosts/spirits, whilst Mashetani is better suited to mean Demon as it has more of an evil/satan connotation.
Are two meanings of " pepo" : 1) cl. 11/10 winds, breezes 2) cl. 1/2 fairy, spirit, demon.
cl. 11/10 - upepo ( sing) > pepo ( pl) ; cl. 1/2 - pepo > mapepo.
I think it would also be "pepo" (as singular and plural):
From Wiktionary: https://en.wiktionary.org/wiki/pepo
What I like is that this seems to be related to upepo, 'wind'
Asante sana rafiki! Yes, some texts I read are showing most of the time the words upepo and pepo as wind and winds, respectively. A few times, pepo appears as spirits.
Thought the same. What a nice language!