Every single Japanese person I've seen who attempts to speak English never focuses on phonetics which are extremely important because pronouncing shit correctly is like 70% of the language. Japanese has much fewer phonemes than English so they would have to learn brand new sounds like [th], [r], or [l] but they never fucking do. The brief exception is Korone as seen in this clip https://www.youtube.com/watch?v=N3YJeCMifZI which is legitimately a break from the Japanese mindset of using katakana to pronounce English. You can see her actually using the schwa vowel rather than the katakana ア, and the theta [θ] rather than ス. This is exactly what you're supposed to do but the elevens find this too difficult as Korone herself mentions in the video and so they give up. This is also why Peo's written English is leagues better than her spoken English. You can see she understands the grammar and sentence structure but when she speaks it it doesn't sound anything like English. For some reason, people who learn English first and then Japanese later (Kiara, Coco, Bae) seem to speak both languages really well but people who learn Japanese first and then attempt to learn English later always fail at the pronunciation (Peo, Beatani, That Japanese Guy Yuta, etc). You'd think that making content in English and being forced to speak it every day would improve their pronunciation but in order to do that they would have to actually learn brand new sounds through sheer willpower and I've never seen any Jap do that.