I’m from Vietnam. I’ve been in the UK for 10 years now. When I met my English husband 13 years ago at 19 I knew 0 English. We communicated using machine translation. So that’s when I started learning English. Fast forward to present day after immersion, living in an English speaking country, formal study, etc. and I’d say my writing and listening (understanding) are good, but my speaking and reading are still bad. I kind of gave up on trying to become fluent at this point.
Speaking Japanese honestly isn’t too hard. Reading/writing Japanese is more difficult but is easier as you realize the complex Kanji are just combinations of simpler kanji and how those relate to meaning. Most of the sounds are also in English.