Im just guessing but to me it seems like when you translate "makemake" as "want" its about something specific and then id translate this sentence as "i want the banana". But when you translate "makemake" as "like" it can be a general statement like "i like banana(s)" as well as "i like the banana" (although then youd probably rather talk about "this/that banana").
I wonder what would make this statement turn into "I like the banana." I also wonder if the above people are right and that "ka" indicates less specific situations such as this one, whereas "nā" might be something like "I wnt that bananas." I know I'm totally repeating, but, I don't know, that's just what it seems to indicate.