I dug into it a little, and I found an interview in which Sami says that Jocke often writes lyrics in English first (or at least he used, it was in the old Sonic interview that they released as a book last year), so it wasn't a big transition for the band to release them in English. Jocke did the translations himself and Chris Gordon "helped" him (which can mean that they discussed until it was perfect or that he only proofed it, or anything on that scale). And then I found this article:
http://www.gradvall.se/artiklar.asp?entry_id=295
The relevant part where Jocke talks about these albums is:
"Everyone thinks that the Swedish versions of Isola and Hagnesta Hill are the originals and the English versions are compromises. This is not entirely true. Many of those songs were actually written in English from the beginning. (There are also two kent songs that only exist in English). But even this underlines what we talked about earlier: most people listen to the vocals as an instrument. The lyrics are secondary."
Jocke didn't specify which ones are the originally English songs, at least I couldn't find any info on that. 747 might have been one of those, because I have a vague memory of him mentioning that but maybe it was at a gig or it is just my brain messing with me, because I cannot find any source of that.
I didn't really help you out here, did I?