I can empathise with the sense of frustration you aptly and expertly describe about the need to write in English. I do not have that same problem being a native-speaker of English, but I would like to add two brief points to your message.
The first is that academic language needs to be learnt by all, regardless of their native language background (Wellington, Bathmaker, Hunt, McCulloch, & Sikes, 2005). Scholarly writing involves reconceptualising one’s identity and becoming comfortable with uncertainty (ibid.) during the process the novice researcher tries to find their voice. Few escape the negativities of guilt, fear and anxiety as developing writers (Murray, 2005). My own journey into academic writing is still characterised by the haziness of confusion as to what is really expected of me. I can write grammatically correct sentences without worrying about what is acceptable in formal terms, but that skill only takes native speakers of English so far. The rest is the journey itself.
The second point I’d like to make turns the notion of the advantage the native speaker of English (NSE) has in Japan on its head. Being the only NSE in my faculty, I’m often asked about the accuracy of colleagues’ academic prose. It is expected that I know the answers to every writing problem I am asked. Yet more often than not, the problems given to me are less to do with writing than to do with the thinking behind the writing and are often issues of academic culture that speak to the same discomfort I mentioned already. However, there is little support for NSE writers in Japan. Murray, Thow, Moore and Murphy (2008) emphasise the value of writing groups and writing consultations to the novice writer. The Japan Association of Language Teaching (JALT) started a web-based group recently, and beyond that there is a paucity of face-to-face help available to the early-career NSE academic in Japan.
I do not make these points to minimise or reject your situation. However, your post gave me the opportunity to articulate an uncommon point in the Japan context.
Murray, R. (2005). Writing For Academic Journals. Maidenhead: Open University Press.
Murray, R., Thow, M., Moore, S., & Murphy, M. (2008). The writing consultation: developing academic writing practices. Journal of Further and Higher Education, 32(2), 119–128. http://doi.org/10.1080/03098770701851854
Wellington, J., Bathmaker, A. M., Hunt, C., McCulloch, G., & Sikes, P. (2005). Succeeding with your doctorate. London: Sage.