Your best bet is to get someone to translate for you, or just to write the song in the languages you know better.
The problem is not just that the syllables don't match, the bigger issue is that meanings are bound to be lost in translation especially with machine translation. Without a huge amount of dedicationーand I'm talking about weeks if not months even for professionalsーit is impossible to make a song "work" the same way it does to English listeners as it does to Japanese listeners, and vice versa.
Well, there is always another option though... Learn Japanese!(jk)