Writing ‘a popular TTS character called ずんだもん (zundamon)’ takes you very little time and gives readers a little more to work with, and which they can use to Google English language resources on the subject if they are interested.
https://www.google.com/search?q=zundamon produces English language resources.
The strongest plausible interpretation is that when keywords are in another language, it is best to give the original language keyword rather than the anglecised/romanised version (which is so often incorrect e.g. Huawei's Tau[1]). It is also plausible that English is their second language.
Speaking higher is politer, and noticeably dropping your pitch is threatening. You probably would pitch-up when speaking to your boss, and people working in shops or restaurants nearly sing welcome/thank you for coming type things.
Does the entire Japanese population learn these things while growing up?