After how Japan mangles names and words into katakana I can’t get too worked up over languages without (formally transcibed) vowel length forget a macron or double letter in publications for non-speakers.
Besides, I don’t think the h thrown into Ohtani is gonna make Dodgers fans say his name any different than without it. It would be similar to trying to get a random Japanese person to use vowels outside the five sounds they have.
I like the story, but as a kid’s show it’s a little bit on the "simple solutions always work " side of things. Like the first thing the kids come up with fixes the problem. It’d be like if in the other shows reversing the polarity or shooting tachyon beams worked right away, rather than being the first failed idea in the problem-solving process.
Also a lot of science ex machina going on.