I recall Mabaa being able to speak actual words (the first Witch Mass we see), so how come in the later chapters all she says is "Nyamu"?
As far as I know, there’s really no clear-cut answer as to why she says “Nyamu” instead of speaking in normal words in later chapters. Like at all.
The only answer I can think of is that she’s purposely weird from Kim’s statements in Chapter 98 in which she says “I don’t think anyone would ever imagine that the way to reach the Witch World is by writing butt letters…Maba-sama…this ritual really shows your age…”.
She might like a Lord Death/Franken Stein case of being weird for the sole sake of it but even saying so sorta stretches it. – Jay